• linux系统调优


    kernel.sched_child_runs_first = 0
    kernel.sched_min_granularity_ns = 3000000
    kernel.sched_latency_ns = 15000000
    kernel.sched_wakeup_granularity_ns = 3000000
    kernel.sched_tunable_scaling = 1
    kernel.sched_features = 3183
    kernel.sched_migration_cost = 500000
    kernel.sched_nr_migrate = 32
    kernel.sched_time_avg = 1000
    kernel.sched_shares_window = 10000000
    kernel.timer_migration = 1
    kernel.sched_rt_period_us = 1000000
    kernel.sched_rt_runtime_us = 950000
    kernel.sched_compat_yield = 0
    kernel.sched_rr_timeslice_ms = 100
    kernel.sched_autogroup_enabled = 0
    kernel.sched_cfs_bandwidth_slice_us = 5000
    kernel.panic = 0
    kernel.exec-shield = 1
    kernel.core_uses_pid = 1
    kernel.core_pattern = core
    kernel.core_pipe_limit = 0
    kernel.tainted = 0
    kernel.real-root-dev = 0
    kernel.print-fatal-signals = 0
    kernel.ctrl-alt-del = 0
    kernel.ftrace_enabled = 1
    kernel.stack_tracer_enabled = 0
    kernel.ftrace_dump_on_oops = 0
    kernel.modprobe = /sbin/modprobe
    kernel.modules_disabled = 0
    kernel.kexec_load_disabled = 0
    kernel.hotplug = 
    kernel.acct = 4    2    30
    kernel.sysrq = 0
    kernel.cad_pid = 1
    kernel.threads-max = 62803
    kernel.random.poolsize = 4096
    kernel.random.entropy_avail = 168
    kernel.random.read_wakeup_threshold = 64
    kernel.random.write_wakeup_threshold = 128
    kernel.random.boot_id = 3b7f0235-9995-4885-91ce-ea8f614896ac
    kernel.random.uuid = 349859da-0492-4b69-aaba-eef98ad0a663
    kernel.usermodehelper.bset = 4294967295    4294967295
    kernel.usermodehelper.inheritable = 4294967295    4294967295
    kernel.overflowuid = 65534
    kernel.overflowgid = 65534
    kernel.pid_max = 32768
    kernel.panic_on_oops = 1
    kernel.printk = 4    4    1    7
    kernel.printk_ratelimit = 5
    kernel.printk_ratelimit_burst = 10
    kernel.printk_delay = 0
    kernel.dmesg_restrict = 0
    kernel.kptr_restrict = 1
    kernel.ngroups_max = 65536
    kernel.cap_last_cap = 33
    kernel.watchdog = 1
    kernel.watchdog_thresh = 60
    kernel.softlockup_panic = 0
    kernel.softlockup_all_cpu_backtrace = 0
    kernel.nmi_watchdog = 1
    kernel.unknown_nmi_panic = 0
    kernel.panic_on_unrecovered_nmi = 0
    kernel.panic_on_io_nmi = 0
    kernel.bootloader_type = 113
    kernel.bootloader_version = 1
    kernel.kstack_depth_to_print = 12
    kernel.io_delay_type = 0
    kernel.randomize_va_space = 2
    kernel.acpi_video_flags = 0
    kernel.hung_task_panic = 0
    kernel.hung_task_check_count = 4194304
    kernel.hung_task_timeout_secs = 120
    kernel.hung_task_warnings = 10
    kernel.compat-log = 1
    kernel.max_lock_depth = 1024
    kernel.poweroff_cmd = /sbin/poweroff
    kernel.keys.maxkeys = 200
    kernel.keys.maxbytes = 20000
    kernel.keys.root_maxkeys = 1000000
    kernel.keys.root_maxbytes = 25000000
    kernel.keys.gc_delay = 300
    kernel.slow-work.min-threads = 2
    kernel.slow-work.max-threads = 4
    kernel.slow-work.vslow-percentage = 50
    kernel.perf_event_paranoid = 1
    kernel.perf_event_mlock_kb = 516
    kernel.perf_event_max_sample_rate = 100000
    kernel.blk_iopoll = 1
    kernel.panic_on_warn = 0
    kernel.sched_domain.cpu0.domain0.min_interval = 1
    kernel.sched_domain.cpu0.domain0.max_interval = 4
    kernel.sched_domain.cpu0.domain0.busy_idx = 2
    kernel.sched_domain.cpu0.domain0.idle_idx = 0
    kernel.sched_domain.cpu0.domain0.newidle_idx = 0
    kernel.sched_domain.cpu0.domain0.wake_idx = 0
    kernel.sched_domain.cpu0.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu0.domain0.busy_factor = 64
    kernel.sched_domain.cpu0.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu0.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu0.domain0.flags = 4655
    kernel.sched_domain.cpu0.domain0.name = MC
    kernel.sched_domain.cpu1.domain0.min_interval = 1
    kernel.sched_domain.cpu1.domain0.max_interval = 4
    kernel.sched_domain.cpu1.domain0.busy_idx = 2
    kernel.sched_domain.cpu1.domain0.idle_idx = 0
    kernel.sched_domain.cpu1.domain0.newidle_idx = 0
    kernel.sched_domain.cpu1.domain0.wake_idx = 0
    kernel.sched_domain.cpu1.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu1.domain0.busy_factor = 64
    kernel.sched_domain.cpu1.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu1.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu1.domain0.flags = 4655
    kernel.sched_domain.cpu1.domain0.name = MC
    kernel.sched_domain.cpu2.domain0.min_interval = 1
    kernel.sched_domain.cpu2.domain0.max_interval = 4
    kernel.sched_domain.cpu2.domain0.busy_idx = 2
    kernel.sched_domain.cpu2.domain0.idle_idx = 0
    kernel.sched_domain.cpu2.domain0.newidle_idx = 0
    kernel.sched_domain.cpu2.domain0.wake_idx = 0
    kernel.sched_domain.cpu2.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu2.domain0.busy_factor = 64
    kernel.sched_domain.cpu2.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu2.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu2.domain0.flags = 4655
    kernel.sched_domain.cpu2.domain0.name = MC
    kernel.sched_domain.cpu3.domain0.min_interval = 1
    kernel.sched_domain.cpu3.domain0.max_interval = 4
    kernel.sched_domain.cpu3.domain0.busy_idx = 2
    kernel.sched_domain.cpu3.domain0.idle_idx = 0
    kernel.sched_domain.cpu3.domain0.newidle_idx = 0
    kernel.sched_domain.cpu3.domain0.wake_idx = 0
    kernel.sched_domain.cpu3.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu3.domain0.busy_factor = 64
    kernel.sched_domain.cpu3.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu3.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu3.domain0.flags = 4655
    kernel.sched_domain.cpu3.domain0.name = MC
    kernel.vsyscall64 = 1
    kernel.ostype = Linux
    kernel.osrelease = 2.6.32-573.22.1.el6.x86_64
    kernel.version = #1 SMP Wed Mar 23 03:35:39 UTC 2016
    kernel.hostname = ap-uce-uop-mq
    kernel.domainname = (none)
    kernel.pty.max = 4096
    kernel.pty.nr = 1
    kernel.shmmax = 68719476736
    kernel.shmall = 4294967296
    kernel.shmmni = 4096
    kernel.shm_rmid_forced = 0
    kernel.msgmax = 65536
    kernel.msgmni = 15737
    kernel.msgmnb = 65536
    kernel.sem = 250    32000    32    128
    kernel.auto_msgmni = 1
    vm.overcommit_memory = 0
    vm.panic_on_oom = 0
    vm.oom_kill_allocating_task = 0
    vm.extfrag_threshold = 500
    vm.oom_dump_tasks = 1
    vm.would_have_oomkilled = 0
    vm.overcommit_ratio = 50
    vm.overcommit_kbytes = 0
    vm.page-cluster = 3
    vm.dirty_background_ratio = 10
    vm.dirty_background_bytes = 0
    vm.dirty_ratio = 20
    vm.dirty_bytes = 0
    vm.dirty_writeback_centisecs = 500
    vm.dirty_expire_centisecs = 3000
    vm.nr_pdflush_threads = 0
    vm.swappiness = 0
    vm.nr_hugepages = 0
    vm.nr_hugepages_mempolicy = 0
    vm.hugetlb_shm_group = 0
    vm.hugepages_treat_as_movable = 0
    vm.nr_overcommit_hugepages = 0
    vm.lowmem_reserve_ratio = 256    256    32
    vm.drop_caches = 0
    vm.min_free_kbytes = 67584
    vm.extra_free_kbytes = 0
    vm.unmap_area_factor = 0
    vm.meminfo_legacy_layout = 1
    vm.percpu_pagelist_fraction = 0
    vm.max_map_count = 65530
    vm.laptop_mode = 0
    vm.block_dump = 0
    vm.vfs_cache_pressure = 100
    vm.legacy_va_layout = 0
    vm.zone_reclaim_mode = 0
    vm.min_unmapped_ratio = 1
    vm.min_slab_ratio = 5
    vm.stat_interval = 1
    vm.mmap_min_addr = 4096
    vm.numa_zonelist_order = default
    vm.scan_unevictable_pages = 0
    vm.memory_failure_early_kill = 0
    vm.memory_failure_recovery = 1
    vm.admin_reserve_kbytes = 8192
    fs.inode-nr = 43147    2072
    fs.inode-state = 43147    2072    0    0    0    0    0
    fs.file-nr = 736    0    798336
    fs.file-max = 798336
    fs.nr_open = 1048576
    fs.dentry-state = 43591    37426    45    0    0    0
    fs.overflowuid = 65534
    fs.overflowgid = 65534
    fs.leases-enable = 1
    fs.dir-notify-enable = 1
    fs.lease-break-time = 45
    fs.aio-nr = 0
    fs.aio-max-nr = 65536
    fs.inotify.max_user_instances = 128
    fs.inotify.max_user_watches = 8192
    fs.inotify.max_queued_events = 16384
    fs.epoll.max_user_watches = 1646346
    fs.suid_dumpable = 0
    fs.binfmt_misc.status = enabled
    fs.quota.lookups = 0
    fs.quota.drops = 0
    fs.quota.reads = 0
    fs.quota.writes = 0
    fs.quota.cache_hits = 0
    fs.quota.allocated_dquots = 0
    fs.quota.free_dquots = 0
    fs.quota.syncs = 2
    fs.quota.warnings = 1
    fs.mqueue.queues_max = 256
    fs.mqueue.msg_max = 10
    fs.mqueue.msgsize_max = 8192
    fs.mqueue.msg_default = 10
    fs.mqueue.msgsize_default = 8192
    fs.nfs.nlm_grace_period = 0
    fs.nfs.nlm_timeout = 10
    fs.nfs.nlm_udpport = 0
    fs.nfs.nlm_tcpport = 0
    fs.nfs.nsm_use_hostnames = 0
    fs.nfs.nsm_local_state = 0
    fs.nfs.nfs_callback_tcpport = 0
    fs.nfs.idmap_cache_timeout = 600
    fs.nfs.nfs_mountpoint_timeout = 500
    fs.nfs.nfs_congestion_kb = 90816
    debug.exception-trace = 1
    debug.kprobes-optimization = 1
    dev.scsi.logging_level = 0
    dev.raid.speed_limit_min = 1000
    dev.raid.speed_limit_max = 200000
    dev.hpet.max-user-freq = 64
    dev.mac_hid.mouse_button_emulation = 0
    dev.mac_hid.mouse_button2_keycode = 97
    dev.mac_hid.mouse_button3_keycode = 100
    dev.cdrom.info = CD-ROM information, Id: cdrom.c 3.20 2003/12/17
    dev.cdrom.info = 
    dev.cdrom.info = drive name:        sr0
    dev.cdrom.info = drive speed:        4
    dev.cdrom.info = drive # of slots:    1
    dev.cdrom.info = Can close tray:        1
    dev.cdrom.info = Can open tray:        1
    dev.cdrom.info = Can lock tray:        1
    dev.cdrom.info = Can change speed:    1
    dev.cdrom.info = Can select disk:    0
    dev.cdrom.info = Can read multisession:    1
    dev.cdrom.info = Can read MCN:        1
    dev.cdrom.info = Reports media changed:    1
    dev.cdrom.info = Can play audio:        1
    dev.cdrom.info = Can write CD-R:        0
    dev.cdrom.info = Can write CD-RW:    0
    dev.cdrom.info = Can read DVD:        1
    dev.cdrom.info = Can write DVD-R:    0
    dev.cdrom.info = Can write DVD-RAM:    0
    dev.cdrom.info = Can read MRW:        1
    dev.cdrom.info = Can write MRW:        1
    dev.cdrom.info = Can write RAM:        1
    dev.cdrom.info = 
    dev.cdrom.info = 
    dev.cdrom.autoclose = 1
    dev.cdrom.autoeject = 0
    dev.cdrom.debug = 0
    dev.cdrom.lock = 1
    dev.cdrom.check_media = 0
    net.netfilter.nf_log.0 = NONE
    net.netfilter.nf_log.1 = NONE
    net.netfilter.nf_log.2 = NONE
    net.netfilter.nf_log.3 = NONE
    net.netfilter.nf_log.4 = NONE
    net.netfilter.nf_log.5 = NONE
    net.netfilter.nf_log.6 = NONE
    net.netfilter.nf_log.7 = NONE
    net.netfilter.nf_log.8 = NONE
    net.netfilter.nf_log.9 = NONE
    net.netfilter.nf_log.10 = NONE
    net.netfilter.nf_log.11 = NONE
    net.netfilter.nf_log.12 = NONE
    net.core.somaxconn = 128
    net.core.xfrm_aevent_etime = 10
    net.core.xfrm_aevent_rseqth = 2
    net.core.xfrm_larval_drop = 1
    net.core.xfrm_acq_expires = 30
    net.core.wmem_max = 124928
    net.core.rmem_max = 124928
    net.core.wmem_default = 124928
    net.core.rmem_default = 124928
    net.core.dev_weight = 64
    net.core.netdev_max_backlog = 1000
    net.core.netdev_rss_key = 00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
    net.core.message_cost = 5
    net.core.message_burst = 10
    net.core.optmem_max = 20480
    net.core.rps_sock_flow_entries = 0
    net.core.busy_poll = 0
    net.core.busy_read = 0
    net.core.netdev_budget = 300
    net.core.warnings = 1
    net.ipv4.route.gc_thresh = 262144
    net.ipv4.route.max_size = 4194304
    net.ipv4.route.gc_min_interval = 0
    net.ipv4.route.gc_min_interval_ms = 500
    net.ipv4.route.gc_timeout = 300
    net.ipv4.route.gc_interval = 60
    net.ipv4.route.redirect_load = 20
    net.ipv4.route.redirect_number = 9
    net.ipv4.route.redirect_silence = 20480
    net.ipv4.route.error_cost = 1000
    net.ipv4.route.error_burst = 5000
    net.ipv4.route.gc_elasticity = 8
    net.ipv4.route.mtu_expires = 600
    net.ipv4.route.min_pmtu = 552
    net.ipv4.route.min_adv_mss = 256
    net.ipv4.route.secret_interval = 600
    net.ipv4.neigh.default.mcast_solicit = 3
    net.ipv4.neigh.default.ucast_solicit = 3
    net.ipv4.neigh.default.app_solicit = 0
    net.ipv4.neigh.default.retrans_time = 99
    net.ipv4.neigh.default.base_reachable_time = 30
    net.ipv4.neigh.default.delay_first_probe_time = 5
    net.ipv4.neigh.default.gc_stale_time = 120
    net.ipv4.neigh.default.unres_qlen = 3
    net.ipv4.neigh.default.proxy_qlen = 64
    net.ipv4.neigh.default.anycast_delay = 99
    net.ipv4.neigh.default.proxy_delay = 79
    net.ipv4.neigh.default.locktime = 99
    net.ipv4.neigh.default.retrans_time_ms = 1000
    net.ipv4.neigh.default.base_reachable_time_ms = 30000
    net.ipv4.neigh.default.gc_interval = 30
    net.ipv4.neigh.default.gc_thresh1 = 128
    net.ipv4.neigh.default.gc_thresh2 = 512
    net.ipv4.neigh.default.gc_thresh3 = 1024
    net.ipv4.neigh.lo.mcast_solicit = 3
    net.ipv4.neigh.lo.ucast_solicit = 3
    net.ipv4.neigh.lo.app_solicit = 0
    net.ipv4.neigh.lo.retrans_time = 99
    net.ipv4.neigh.lo.base_reachable_time = 30
    net.ipv4.neigh.lo.delay_first_probe_time = 5
    net.ipv4.neigh.lo.gc_stale_time = 60
    net.ipv4.neigh.lo.unres_qlen = 3
    net.ipv4.neigh.lo.proxy_qlen = 64
    net.ipv4.neigh.lo.anycast_delay = 99
    net.ipv4.neigh.lo.proxy_delay = 79
    net.ipv4.neigh.lo.locktime = 99
    net.ipv4.neigh.lo.retrans_time_ms = 1000
    net.ipv4.neigh.lo.base_reachable_time_ms = 30000
    net.ipv4.neigh.eth0.mcast_solicit = 3
    net.ipv4.neigh.eth0.ucast_solicit = 3
    net.ipv4.neigh.eth0.app_solicit = 0
    net.ipv4.neigh.eth0.retrans_time = 99
    net.ipv4.neigh.eth0.base_reachable_time = 30
    net.ipv4.neigh.eth0.delay_first_probe_time = 5
    net.ipv4.neigh.eth0.gc_stale_time = 120
    net.ipv4.neigh.eth0.unres_qlen = 3
    net.ipv4.neigh.eth0.proxy_qlen = 64
    net.ipv4.neigh.eth0.anycast_delay = 99
    net.ipv4.neigh.eth0.proxy_delay = 79
    net.ipv4.neigh.eth0.locktime = 99
    net.ipv4.neigh.eth0.retrans_time_ms = 1000
    net.ipv4.neigh.eth0.base_reachable_time_ms = 30000
    net.ipv4.tcp_timestamps = 1
    net.ipv4.tcp_window_scaling = 1
    net.ipv4.tcp_sack = 1
    net.ipv4.tcp_retrans_collapse = 1
    net.ipv4.ip_default_ttl = 64
    net.ipv4.ip_nonlocal_bind = 0
    net.ipv4.tcp_syn_retries = 5
    net.ipv4.tcp_synack_retries = 2
    net.ipv4.tcp_max_orphans = 262144
    net.ipv4.tcp_max_tw_buckets = 5000
    net.ipv4.ip_dynaddr = 0
    net.ipv4.tcp_keepalive_time = 7200
    net.ipv4.tcp_keepalive_probes = 9
    net.ipv4.tcp_keepalive_intvl = 75
    net.ipv4.tcp_retries1 = 3
    net.ipv4.tcp_retries2 = 15
    net.ipv4.tcp_fin_timeout = 60
    net.ipv4.tcp_syncookies = 1
    net.ipv4.tcp_tw_recycle = 0
    net.ipv4.tcp_abort_on_overflow = 0
    net.ipv4.tcp_stdurg = 0
    net.ipv4.tcp_rfc1337 = 0
    net.ipv4.tcp_max_syn_backlog = 1024
    net.ipv4.ip_local_port_range = 32768    61000
    net.ipv4.ip_local_reserved_ports = 
    net.ipv4.igmp_max_memberships = 20
    net.ipv4.igmp_max_msf = 10
    net.ipv4.inet_peer_threshold = 65664
    net.ipv4.inet_peer_minttl = 120
    net.ipv4.inet_peer_maxttl = 600
    net.ipv4.inet_peer_gc_mintime = 10
    net.ipv4.inet_peer_gc_maxtime = 120
    net.ipv4.tcp_orphan_retries = 0
    net.ipv4.tcp_fack = 1
    net.ipv4.tcp_reordering = 3
    net.ipv4.tcp_ecn = 2
    net.ipv4.tcp_dsack = 1
    net.ipv4.tcp_mem = 753600    1004800    1507200
    net.ipv4.tcp_wmem = 4096    16384    4194304
    net.ipv4.tcp_rmem = 4096    87380    4194304
    net.ipv4.tcp_app_win = 31
    net.ipv4.tcp_adv_win_scale = 2
    net.ipv4.tcp_tw_reuse = 0
    net.ipv4.tcp_frto = 2
    net.ipv4.tcp_frto_response = 0
    net.ipv4.tcp_low_latency = 0
    net.ipv4.tcp_no_metrics_save = 0
    net.ipv4.tcp_moderate_rcvbuf = 1
    net.ipv4.tcp_tso_win_divisor = 3
    net.ipv4.tcp_congestion_control = cubic
    net.ipv4.tcp_abc = 0
    net.ipv4.tcp_mtu_probing = 0
    net.ipv4.tcp_base_mss = 512
    net.ipv4.tcp_workaround_signed_windows = 0
    net.ipv4.tcp_challenge_ack_limit = 100
    net.ipv4.tcp_limit_output_bytes = 262144
    net.ipv4.tcp_dma_copybreak = 4096
    net.ipv4.tcp_slow_start_after_idle = 1
    net.ipv4.cipso_cache_enable = 1
    net.ipv4.cipso_cache_bucket_size = 10
    net.ipv4.cipso_rbm_optfmt = 0
    net.ipv4.cipso_rbm_strictvalid = 1
    net.ipv4.tcp_available_congestion_control = cubic reno
    net.ipv4.tcp_allowed_congestion_control = cubic reno
    net.ipv4.tcp_max_ssthresh = 0
    net.ipv4.tcp_thin_linear_timeouts = 0
    net.ipv4.tcp_thin_dupack = 0
    net.ipv4.tcp_min_tso_segs = 2
    net.ipv4.udp_mem = 753600    1004800    1507200
    net.ipv4.udp_rmem_min = 4096
    net.ipv4.udp_wmem_min = 4096
    net.ipv4.conf.all.forwarding = 0
    net.ipv4.conf.all.mc_forwarding = 0
    net.ipv4.conf.all.accept_redirects = 1
    net.ipv4.conf.all.secure_redirects = 1
    net.ipv4.conf.all.shared_media = 1
    net.ipv4.conf.all.rp_filter = 0
    net.ipv4.conf.all.send_redirects = 1
    net.ipv4.conf.all.accept_source_route = 0
    net.ipv4.conf.all.src_valid_mark = 0
    net.ipv4.conf.all.proxy_arp = 0
    net.ipv4.conf.all.medium_id = 0
    net.ipv4.conf.all.bootp_relay = 0
    net.ipv4.conf.all.log_martians = 0
    net.ipv4.conf.all.tag = 0
    net.ipv4.conf.all.arp_filter = 0
    net.ipv4.conf.all.arp_announce = 2
    net.ipv4.conf.all.arp_ignore = 0
    net.ipv4.conf.all.arp_accept = 0
    net.ipv4.conf.all.arp_notify = 0
    net.ipv4.conf.all.proxy_arp_pvlan = 0
    net.ipv4.conf.all.disable_xfrm = 0
    net.ipv4.conf.all.disable_policy = 0
    net.ipv4.conf.all.force_igmp_version = 0
    net.ipv4.conf.all.promote_secondaries = 0
    net.ipv4.conf.all.accept_local = 0
    net.ipv4.conf.all.route_localnet = 0
    net.ipv4.conf.default.forwarding = 0
    net.ipv4.conf.default.mc_forwarding = 0
    net.ipv4.conf.default.accept_redirects = 1
    net.ipv4.conf.default.secure_redirects = 1
    net.ipv4.conf.default.shared_media = 1
    net.ipv4.conf.default.rp_filter = 0
    net.ipv4.conf.default.send_redirects = 1
    net.ipv4.conf.default.accept_source_route = 0
    net.ipv4.conf.default.src_valid_mark = 0
    net.ipv4.conf.default.proxy_arp = 0
    net.ipv4.conf.default.medium_id = 0
    net.ipv4.conf.default.bootp_relay = 0
    net.ipv4.conf.default.log_martians = 0
    net.ipv4.conf.default.tag = 0
    net.ipv4.conf.default.arp_filter = 0
    net.ipv4.conf.default.arp_announce = 2
    net.ipv4.conf.default.arp_ignore = 0
    net.ipv4.conf.default.arp_accept = 0
    net.ipv4.conf.default.arp_notify = 0
    net.ipv4.conf.default.proxy_arp_pvlan = 0
    net.ipv4.conf.default.disable_xfrm = 0
    net.ipv4.conf.default.disable_policy = 0
    net.ipv4.conf.default.force_igmp_version = 0
    net.ipv4.conf.default.promote_secondaries = 0
    net.ipv4.conf.default.accept_local = 0
    net.ipv4.conf.default.route_localnet = 0
    net.ipv4.conf.lo.forwarding = 0
    net.ipv4.conf.lo.mc_forwarding = 0
    net.ipv4.conf.lo.accept_redirects = 1
    net.ipv4.conf.lo.secure_redirects = 1
    net.ipv4.conf.lo.shared_media = 1
    net.ipv4.conf.lo.rp_filter = 0
    net.ipv4.conf.lo.send_redirects = 1
    net.ipv4.conf.lo.accept_source_route = 1
    net.ipv4.conf.lo.src_valid_mark = 0
    net.ipv4.conf.lo.proxy_arp = 0
    net.ipv4.conf.lo.medium_id = 0
    net.ipv4.conf.lo.bootp_relay = 0
    net.ipv4.conf.lo.log_martians = 0
    net.ipv4.conf.lo.tag = 0
    net.ipv4.conf.lo.arp_filter = 0
    net.ipv4.conf.lo.arp_announce = 2
    net.ipv4.conf.lo.arp_ignore = 0
    net.ipv4.conf.lo.arp_accept = 0
    net.ipv4.conf.lo.arp_notify = 0
    net.ipv4.conf.lo.proxy_arp_pvlan = 0
    net.ipv4.conf.lo.disable_xfrm = 1
    net.ipv4.conf.lo.disable_policy = 1
    net.ipv4.conf.lo.force_igmp_version = 0
    net.ipv4.conf.lo.promote_secondaries = 0
    net.ipv4.conf.lo.accept_local = 0
    net.ipv4.conf.lo.route_localnet = 0
    net.ipv4.conf.eth0.forwarding = 0
    net.ipv4.conf.eth0.mc_forwarding = 0
    net.ipv4.conf.eth0.accept_redirects = 1
    net.ipv4.conf.eth0.secure_redirects = 1
    net.ipv4.conf.eth0.shared_media = 1
    net.ipv4.conf.eth0.rp_filter = 0
    net.ipv4.conf.eth0.send_redirects = 1
    net.ipv4.conf.eth0.accept_source_route = 0
    net.ipv4.conf.eth0.src_valid_mark = 0
    net.ipv4.conf.eth0.proxy_arp = 0
    net.ipv4.conf.eth0.medium_id = 0
    net.ipv4.conf.eth0.bootp_relay = 0
    net.ipv4.conf.eth0.log_martians = 0
    net.ipv4.conf.eth0.tag = 0
    net.ipv4.conf.eth0.arp_filter = 0
    net.ipv4.conf.eth0.arp_announce = 2
    net.ipv4.conf.eth0.arp_ignore = 0
    net.ipv4.conf.eth0.arp_accept = 0
    net.ipv4.conf.eth0.arp_notify = 0
    net.ipv4.conf.eth0.proxy_arp_pvlan = 0
    net.ipv4.conf.eth0.disable_xfrm = 0
    net.ipv4.conf.eth0.disable_policy = 0
    net.ipv4.conf.eth0.force_igmp_version = 0
    net.ipv4.conf.eth0.promote_secondaries = 0
    net.ipv4.conf.eth0.accept_local = 0
    net.ipv4.conf.eth0.route_localnet = 0
    net.ipv4.ip_forward = 0
    net.ipv4.xfrm4_gc_thresh = 2097152
    net.ipv4.ipfrag_high_thresh = 4194304
    net.ipv4.ipfrag_low_thresh = 3145728
    net.ipv4.ipfrag_time = 30
    net.ipv4.icmp_echo_ignore_all = 0
    net.ipv4.icmp_echo_ignore_broadcasts = 1
    net.ipv4.icmp_ignore_bogus_error_responses = 1
    net.ipv4.icmp_errors_use_inbound_ifaddr = 0
    net.ipv4.icmp_ratelimit = 1000
    net.ipv4.icmp_ratemask = 6168
    net.ipv4.rt_cache_rebuild_count = 4
    net.ipv4.ping_group_range = 1    0
    net.ipv4.ip_no_pmtu_disc = 0
    net.ipv4.ip_forward_use_pmtu = 0
    net.ipv4.ipfrag_secret_interval = 600
    net.ipv4.ipfrag_max_dist = 64
    net.unix.max_dgram_qlen = 10
    abi.vsyscall32 = 1
    crypto.fips_enabled = 0
    sunrpc.rpc_debug = 0
    sunrpc.nfs_debug = 0
    sunrpc.nfsd_debug = 0
    sunrpc.nlm_debug = 0
    sunrpc.transports = tcp 1048576
    sunrpc.transports = udp 32768
    sunrpc.transports = tcp-bc 1048576
    sunrpc.udp_slot_table_entries = 16
    sunrpc.tcp_slot_table_entries = 2
    sunrpc.tcp_max_slot_table_entries = 65536
    sunrpc.min_resvport = 665
    sunrpc.max_resvport = 1023
    sunrpc.tcp_fin_timeout = 15
    阿里云内核参数

     kernel.sched_child_runs_first = 0
    sysctl_sched_child_runs_first,该变量表示在创建子进程的时候是否让子进程抢占父进程,即使父进程的vruntime小于子进程,这个会减少公平性,但是可以降低write_on_copy,具体要根据系统的应用情况来考量使用哪种方式(见task_fork_fair过程)

    kernel.sched_min_granularity_ns = 3000000
    (4000000ns):sysctl_sched_min_granularity,表示进程最少运行时间,防止频繁的切换,对于交互系统(如桌面),该值可以设置得较小,这样可以保证交互得到更快的响应(见周期调度器的check_preempt_tick过程)

    kernel.sched_latency_ns = 15000000
    sysctl_sched_latency,表示一个运行队列所有进程运行一次的周期,当前这个与运行队列的进程数有关,如果进程数超过sched_nr_latency(这个变量不能通过/proc设置,它是由(sysctl_sched_latency+ sysctl_sched_min_granularity-1)/sysctl_sched_min_granularity确定的),那么调度周期就是sched_min_granularity_ns*运行队列里的进程数,与sysctl_sched_latency无关;否则队列进程数小于sched_nr_latency,运行周期就是sysctl_sched_latency。显然这个数越小,一个运行队列支持的sched_nr_latency越少,而且当sysctl_sched_min_granularity越小时能支持的sched_nr_latency越多,那么每个进程在这个周期内能执行的时间也就越少,这也与上面sysctl_sched_min_granularity变量的讨论一致。其实sched_nr_latency也可以当做我们cpu load的基准值,如果cpu的load大于这个值,那么说明cpu不够使用了

    kernel.sched_wakeup_granularity_ns = 3000000
    sysctl_sched_wakeup_granularity,该变量表示进程被唤醒后至少应该运行的时间的基数,它只是用来判断某个进程是否应该抢占当前进程,并不代表它能够执行的最小时间(sysctl_sched_min_granularity),如果这个数值越小,那么发生抢占的概率也就越高(见wakeup_gran、wakeup_preempt_entity函数)

    kernel.sched_tunable_scaling = 1
    sysctl_sched_tunable_scaling,当内核试图调整sched_min_granularity,sched_latency和sched_wakeup_granularity这三个值的时候所使用的更新方法,0为不调整,1为按照cpu个数以2为底的对数值进行调整,2为按照cpu的个数进行线性比例的调整

    kernel.sched_features = 3183
    sysctl_sched_features,该变量表示调度器支持的特性,如GENTLE_FAIR_SLEEPERS(平滑的补偿睡眠进程),START_DEBIT(新进程尽量的早调度),WAKEUP_PREEMPT(是否wakeup的进程可以去抢占当前运行的进程)等,所有的features见内核sech_features.h文件的定义

    kernel.sched_migration_cost = 500000
    sysctl_sched_migration_cost该变量用来判断一个进程是否还是hot,如果进程的运行时间(now - p->se.exec_start)小于它,那么内核认为它的code还在cache里,所以该进程还是hot,那么在迁移的时候就不会考虑它

    kernel.sched_nr_migrate = 32
    sysctl_sched_nr_migrate,在多CPU情况下进行负载均衡时,一次最多移动多少个进程到另一个CPU上

    kernel.sched_time_avg = 1000
    kernel.sched_shares_window = 10000000
    kernel.timer_migration = 1
    kernel.sched_rt_period_us = 1000000
    该参数与sched_rt_runtime_us一起决定了实时进程在以sched_rt_period为周期的时间内,实时进程最多能够运行的总的时间不能超过sched_rt_runtime_us

    kernel.sched_rt_runtime_us = 950000
    该参数与sched_rt_period一起决定了实时进程在以sched_rt_period为周期的时间内,实时进程最多能够运行的总的时间不能超过sched_rt_runtime_us

    kernel.sched_compat_yield = 0

    kernel.sched_rr_timeslice_ms = 100
    用来指示round robin调度进程的间隔,这个间隔默认是100ms
    kernel.sched_autogroup_enabled = 0
    启用后,内核会创建任务组来优化桌面程序的调度。它将把占用大量资源的应用程序放在它们自己的任务组,这有助于性能提升
    0:禁止
    1:开启

    kernel.sched_cfs_bandwidth_slice_us = 5000
    kernel.panic = 0
    kernel.exec-shield = 1
    kernel.core_uses_pid = 1
    kernel.core_pattern = core
    kernel.core_pipe_limit = 0
    kernel.tainted = 0
    kernel.real-root-dev = 0
    kernel.print-fatal-signals = 0
    kernel.ctrl-alt-del = 0
    kernel.ftrace_enabled = 1
    kernel.stack_tracer_enabled = 0
    kernel.ftrace_dump_on_oops = 0
    kernel.modprobe = /sbin/modprobe
    kernel.modules_disabled = 0
    kernel.kexec_load_disabled = 0
    kernel.hotplug =
    kernel.acct = 4    2    30
    kernel.sysrq = 0
    kernel.cad_pid = 1
    kernel.threads-max = 62803
    kernel.random.poolsize = 4096
    kernel.random.entropy_avail = 168
    kernel.random.read_wakeup_threshold = 64
    kernel.random.write_wakeup_threshold = 128
    kernel.random.boot_id = 3b7f0235-9995-4885-91ce-ea8f614896ac
    kernel.random.uuid = 349859da-0492-4b69-aaba-eef98ad0a663
    kernel.usermodehelper.bset = 4294967295    4294967295
    kernel.usermodehelper.inheritable = 4294967295    4294967295
    kernel.overflowuid = 65534
    kernel.overflowgid = 65534
    kernel.pid_max = 32768
    kernel.panic_on_oops = 1
    kernel.printk = 4    4    1    7
    kernel.printk_ratelimit = 5
    kernel.printk_ratelimit_burst = 10
    kernel.printk_delay = 0
    kernel.dmesg_restrict = 0
    kernel.kptr_restrict = 1
    kernel.ngroups_max = 65536
    kernel.cap_last_cap = 33
    kernel.watchdog = 1
    kernel.watchdog_thresh = 60
    kernel.softlockup_panic = 0
    设置产生softlockup时是否抛出一个panic。Softlockup用于检测CPU可以响应中断,但是在长时间内不能调度(比如禁止抢占时间太长)的死锁情况。这个机制运行在一个hrtimer的中断上下文,每隔一段时间检测一下是否发生了调度,如果过长时间没发生调度,说明系统被死锁。
    0:不产生panic
    1:产生panic

    kernel.softlockup_all_cpu_backtrace = 0
    kernel.nmi_watchdog = 1
    使能nmi_watchdog
    0:禁止
    1:开启
    kernel.unknown_nmi_panic = 0
    kernel.panic_on_unrecovered_nmi = 0
    kernel.panic_on_io_nmi = 0
    kernel.bootloader_type = 113
    kernel.bootloader_version = 1
    kernel.kstack_depth_to_print = 12
    kernel.io_delay_type = 0
    kernel.randomize_va_space = 2
    kernel.acpi_video_flags = 0
    kernel.hung_task_panic = 0
    kernel.hung_task_check_count = 4194304
    kernel.hung_task_timeout_secs = 120
    kernel.hung_task_warnings = 10
    kernel.compat-log = 1
    kernel.max_lock_depth = 1024
    kernel.poweroff_cmd = /sbin/poweroff
    kernel.keys.maxkeys = 200
    kernel.keys.maxbytes = 20000
    kernel.keys.root_maxkeys = 1000000
    kernel.keys.root_maxbytes = 25000000
    kernel.keys.gc_delay = 300
    kernel.slow-work.min-threads = 2
    kernel.slow-work.max-threads = 4
    kernel.slow-work.vslow-percentage = 50
    kernel.perf_event_paranoid = 1
    kernel.perf_event_mlock_kb = 516
    kernel.perf_event_max_sample_rate = 100000
    kernel.blk_iopoll = 1
    kernel.panic_on_warn = 0
    kernel.sched_domain.cpu0.domain0.min_interval = 1
    kernel.sched_domain.cpu0.domain0.max_interval = 4
    kernel.sched_domain.cpu0.domain0.busy_idx = 2
    kernel.sched_domain.cpu0.domain0.idle_idx = 0
    kernel.sched_domain.cpu0.domain0.newidle_idx = 0
    kernel.sched_domain.cpu0.domain0.wake_idx = 0
    kernel.sched_domain.cpu0.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu0.domain0.busy_factor = 64
    kernel.sched_domain.cpu0.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu0.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu0.domain0.flags = 4655
    kernel.sched_domain.cpu0.domain0.name = MC
    kernel.sched_domain.cpu1.domain0.min_interval = 1
    kernel.sched_domain.cpu1.domain0.max_interval = 4
    kernel.sched_domain.cpu1.domain0.busy_idx = 2
    kernel.sched_domain.cpu1.domain0.idle_idx = 0
    kernel.sched_domain.cpu1.domain0.newidle_idx = 0
    kernel.sched_domain.cpu1.domain0.wake_idx = 0
    kernel.sched_domain.cpu1.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu1.domain0.busy_factor = 64
    kernel.sched_domain.cpu1.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu1.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu1.domain0.flags = 4655
    kernel.sched_domain.cpu1.domain0.name = MC
    kernel.sched_domain.cpu2.domain0.min_interval = 1
    kernel.sched_domain.cpu2.domain0.max_interval = 4
    kernel.sched_domain.cpu2.domain0.busy_idx = 2
    kernel.sched_domain.cpu2.domain0.idle_idx = 0
    kernel.sched_domain.cpu2.domain0.newidle_idx = 0
    kernel.sched_domain.cpu2.domain0.wake_idx = 0
    kernel.sched_domain.cpu2.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu2.domain0.busy_factor = 64
    kernel.sched_domain.cpu2.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu2.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu2.domain0.flags = 4655
    kernel.sched_domain.cpu2.domain0.name = MC
    kernel.sched_domain.cpu3.domain0.min_interval = 1
    kernel.sched_domain.cpu3.domain0.max_interval = 4
    kernel.sched_domain.cpu3.domain0.busy_idx = 2
    kernel.sched_domain.cpu3.domain0.idle_idx = 0
    kernel.sched_domain.cpu3.domain0.newidle_idx = 0
    kernel.sched_domain.cpu3.domain0.wake_idx = 0
    kernel.sched_domain.cpu3.domain0.forkexec_idx = 0
    kernel.sched_domain.cpu3.domain0.busy_factor = 64
    kernel.sched_domain.cpu3.domain0.imbalance_pct = 125
    kernel.sched_domain.cpu3.domain0.cache_nice_tries = 1
    kernel.sched_domain.cpu3.domain0.flags = 4655
    kernel.sched_domain.cpu3.domain0.name = MC
    kernel.vsyscall64 = 1
    kernel.ostype = Linux
    kernel.osrelease = 2.6.32-573.22.1.el6.x86_64
    kernel.version = #1 SMP Wed Mar 23 03:35:39 UTC 2016
    kernel.hostname = ap-uce-uop-mq
    kernel.domainname = (none)
    kernel.pty.max = 4096
    kernel.pty.nr = 1
    kernel.shmmax = 68719476736
    kernel.shmall = 4294967296
    kernel.shmmni = 4096
    kernel.shm_rmid_forced = 0
    kernel.msgmax = 65536
    kernel.msgmni = 15737
    kernel.msgmnb = 65536
    kernel.sem = 250    32000    32    128
    kernel.auto_msgmni = 1
    vm.overcommit_memory = 0
    vm.panic_on_oom = 0
    vm.oom_kill_allocating_task = 0
    vm.extfrag_threshold = 500
    vm.oom_dump_tasks = 1
    vm.would_have_oomkilled = 0
    vm.overcommit_ratio = 50
    vm.overcommit_kbytes = 0
    vm.page-cluster = 3
    vm.dirty_background_ratio = 10
    vm.dirty_background_bytes = 0
    vm.dirty_ratio = 20
    vm.dirty_bytes = 0
    vm.dirty_writeback_centisecs = 500
    vm.dirty_expire_centisecs = 3000
    vm.nr_pdflush_threads = 0
    vm.swappiness = 0
    vm.nr_hugepages = 0
    vm.nr_hugepages_mempolicy = 0
    vm.hugetlb_shm_group = 0
    vm.hugepages_treat_as_movable = 0
    vm.nr_overcommit_hugepages = 0
    vm.lowmem_reserve_ratio = 256    256    32
    vm.drop_caches = 0
    vm.min_free_kbytes = 67584
    vm.extra_free_kbytes = 0
    vm.unmap_area_factor = 0
    vm.meminfo_legacy_layout = 1
    vm.percpu_pagelist_fraction = 0
    vm.max_map_count = 65530
    vm.laptop_mode = 0
    vm.block_dump = 0
    vm.vfs_cache_pressure = 100
    vm.legacy_va_layout = 0
    vm.zone_reclaim_mode = 0
    vm.min_unmapped_ratio = 1
    vm.min_slab_ratio = 5
    vm.stat_interval = 1
    vm.mmap_min_addr = 4096
    vm.numa_zonelist_order = default
    vm.scan_unevictable_pages = 0
    vm.memory_failure_early_kill = 0
    vm.memory_failure_recovery = 1
    vm.admin_reserve_kbytes = 8192
    fs.inode-nr = 43147    2072
    fs.inode-state = 43147    2072    0    0    0    0    0
    fs.file-nr = 736    0    798336
    fs.file-max = 798336
    fs.nr_open = 1048576
    fs.dentry-state = 43591    37426    45    0    0    0
    fs.overflowuid = 65534
    fs.overflowgid = 65534
    fs.leases-enable = 1
    fs.dir-notify-enable = 1
    fs.lease-break-time = 45
    fs.aio-nr = 0
    fs.aio-max-nr = 65536
    fs.inotify.max_user_instances = 128
    fs.inotify.max_user_watches = 8192
    fs.inotify.max_queued_events = 16384
    fs.epoll.max_user_watches = 1646346
    fs.suid_dumpable = 0
    fs.binfmt_misc.status = enabled
    fs.quota.lookups = 0
    fs.quota.drops = 0
    fs.quota.reads = 0
    fs.quota.writes = 0
    fs.quota.cache_hits = 0
    fs.quota.allocated_dquots = 0
    fs.quota.free_dquots = 0
    fs.quota.syncs = 2
    fs.quota.warnings = 1
    fs.mqueue.queues_max = 256
    fs.mqueue.msg_max = 10
    fs.mqueue.msgsize_max = 8192
    fs.mqueue.msg_default = 10
    fs.mqueue.msgsize_default = 8192
    fs.nfs.nlm_grace_period = 0
    fs.nfs.nlm_timeout = 10
    fs.nfs.nlm_udpport = 0
    fs.nfs.nlm_tcpport = 0
    fs.nfs.nsm_use_hostnames = 0
    fs.nfs.nsm_local_state = 0
    fs.nfs.nfs_callback_tcpport = 0
    fs.nfs.idmap_cache_timeout = 600
    fs.nfs.nfs_mountpoint_timeout = 500
    fs.nfs.nfs_congestion_kb = 90816
    debug.exception-trace = 1
    debug.kprobes-optimization = 1
    dev.scsi.logging_level = 0
    dev.raid.speed_limit_min = 1000
    dev.raid.speed_limit_max = 200000
    dev.hpet.max-user-freq = 64
    dev.mac_hid.mouse_button_emulation = 0
    dev.mac_hid.mouse_button2_keycode = 97
    dev.mac_hid.mouse_button3_keycode = 100
    dev.cdrom.info = CD-ROM information, Id: cdrom.c 3.20 2003/12/17
    dev.cdrom.info =
    dev.cdrom.info = drive name:        sr0
    dev.cdrom.info = drive speed:        4
    dev.cdrom.info = drive # of slots:    1
    dev.cdrom.info = Can close tray:        1
    dev.cdrom.info = Can open tray:        1
    dev.cdrom.info = Can lock tray:        1
    dev.cdrom.info = Can change speed:    1
    dev.cdrom.info = Can select disk:    0
    dev.cdrom.info = Can read multisession:    1
    dev.cdrom.info = Can read MCN:        1
    dev.cdrom.info = Reports media changed:    1
    dev.cdrom.info = Can play audio:        1
    dev.cdrom.info = Can write CD-R:        0
    dev.cdrom.info = Can write CD-RW:    0
    dev.cdrom.info = Can read DVD:        1
    dev.cdrom.info = Can write DVD-R:    0
    dev.cdrom.info = Can write DVD-RAM:    0
    dev.cdrom.info = Can read MRW:        1
    dev.cdrom.info = Can write MRW:        1
    dev.cdrom.info = Can write RAM:        1
    dev.cdrom.info =
    dev.cdrom.info =
    dev.cdrom.autoclose = 1
    dev.cdrom.autoeject = 0
    dev.cdrom.debug = 0
    dev.cdrom.lock = 1
    dev.cdrom.check_media = 0
    net.netfilter.nf_log.0 = NONE
    net.netfilter.nf_log.1 = NONE
    net.netfilter.nf_log.2 = NONE
    net.netfilter.nf_log.3 = NONE
    net.netfilter.nf_log.4 = NONE
    net.netfilter.nf_log.5 = NONE
    net.netfilter.nf_log.6 = NONE
    net.netfilter.nf_log.7 = NONE
    net.netfilter.nf_log.8 = NONE
    net.netfilter.nf_log.9 = NONE
    net.netfilter.nf_log.10 = NONE
    net.netfilter.nf_log.11 = NONE
    net.netfilter.nf_log.12 = NONE
    net.core.somaxconn = 128
    net.core.xfrm_aevent_etime = 10
    net.core.xfrm_aevent_rseqth = 2
    net.core.xfrm_larval_drop = 1
    net.core.xfrm_acq_expires = 30
    net.core.wmem_max = 124928
    net.core.rmem_max = 124928
    net.core.wmem_default = 124928
    net.core.rmem_default = 124928
    net.core.dev_weight = 64
    net.core.netdev_max_backlog = 1000
    net.core.netdev_rss_key = 00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
    net.core.message_cost = 5
    net.core.message_burst = 10
    net.core.optmem_max = 20480
    net.core.rps_sock_flow_entries = 0
    net.core.busy_poll = 0
    net.core.busy_read = 0
    net.core.netdev_budget = 300
    net.core.warnings = 1
    net.ipv4.route.gc_thresh = 262144
    net.ipv4.route.max_size = 4194304
    net.ipv4.route.gc_min_interval = 0
    net.ipv4.route.gc_min_interval_ms = 500
    net.ipv4.route.gc_timeout = 300
    net.ipv4.route.gc_interval = 60
    net.ipv4.route.redirect_load = 20
    net.ipv4.route.redirect_number = 9
    net.ipv4.route.redirect_silence = 20480
    net.ipv4.route.error_cost = 1000
    net.ipv4.route.error_burst = 5000
    net.ipv4.route.gc_elasticity = 8
    net.ipv4.route.mtu_expires = 600
    net.ipv4.route.min_pmtu = 552
    net.ipv4.route.min_adv_mss = 256
    net.ipv4.route.secret_interval = 600
    net.ipv4.neigh.default.mcast_solicit = 3
    net.ipv4.neigh.default.ucast_solicit = 3
    net.ipv4.neigh.default.app_solicit = 0
    net.ipv4.neigh.default.retrans_time = 99
    net.ipv4.neigh.default.base_reachable_time = 30
    net.ipv4.neigh.default.delay_first_probe_time = 5
    net.ipv4.neigh.default.gc_stale_time = 120
    net.ipv4.neigh.default.unres_qlen = 3
    net.ipv4.neigh.default.proxy_qlen = 64
    net.ipv4.neigh.default.anycast_delay = 99
    net.ipv4.neigh.default.proxy_delay = 79
    net.ipv4.neigh.default.locktime = 99
    net.ipv4.neigh.default.retrans_time_ms = 1000
    net.ipv4.neigh.default.base_reachable_time_ms = 30000
    net.ipv4.neigh.default.gc_interval = 30
    net.ipv4.neigh.default.gc_thresh1 = 128
    net.ipv4.neigh.default.gc_thresh2 = 512
    net.ipv4.neigh.default.gc_thresh3 = 1024
    net.ipv4.neigh.lo.mcast_solicit = 3
    net.ipv4.neigh.lo.ucast_solicit = 3
    net.ipv4.neigh.lo.app_solicit = 0
    net.ipv4.neigh.lo.retrans_time = 99
    net.ipv4.neigh.lo.base_reachable_time = 30
    net.ipv4.neigh.lo.delay_first_probe_time = 5
    net.ipv4.neigh.lo.gc_stale_time = 60
    net.ipv4.neigh.lo.unres_qlen = 3
    net.ipv4.neigh.lo.proxy_qlen = 64
    net.ipv4.neigh.lo.anycast_delay = 99
    net.ipv4.neigh.lo.proxy_delay = 79
    net.ipv4.neigh.lo.locktime = 99
    net.ipv4.neigh.lo.retrans_time_ms = 1000
    net.ipv4.neigh.lo.base_reachable_time_ms = 30000
    net.ipv4.neigh.eth0.mcast_solicit = 3
    net.ipv4.neigh.eth0.ucast_solicit = 3
    net.ipv4.neigh.eth0.app_solicit = 0
    net.ipv4.neigh.eth0.retrans_time = 99
    net.ipv4.neigh.eth0.base_reachable_time = 30
    net.ipv4.neigh.eth0.delay_first_probe_time = 5
    net.ipv4.neigh.eth0.gc_stale_time = 120
    net.ipv4.neigh.eth0.unres_qlen = 3
    net.ipv4.neigh.eth0.proxy_qlen = 64
    net.ipv4.neigh.eth0.anycast_delay = 99
    net.ipv4.neigh.eth0.proxy_delay = 79
    net.ipv4.neigh.eth0.locktime = 99
    net.ipv4.neigh.eth0.retrans_time_ms = 1000
    net.ipv4.neigh.eth0.base_reachable_time_ms = 30000
    net.ipv4.tcp_timestamps = 1
    缺省值为1
    Timestamps 用在其它一些东西中﹐可以防范那些伪造的 sequence 号码。一条1G的宽带线路或许会重遇到带 out-of-line数值的旧sequence 号码(假如它是由于上次产生的)。Timestamp 会让它知道这是个 '旧封包'。(该文件表示是否启用以一种比超时重发更精确的方法(RFC 1323)来启用对 RTT 的计算;为了实现更好的性能应该启用这个选项。)

    net.ipv4.tcp_window_scaling = 1
    缺省值为1
    该文件表示设置tcp/ip会话的滑动窗口大小是否可变。参数值为布尔值,为1时表示可变,为0时表示不可变。tcp/ip通常使用的窗口最大可达到 65535 字节,对于高速网络,该值可能太小,这时候如果启用了该功能,可以使tcp/ip滑动窗口大小增大数个数量级,从而提高数据传输的能力(RFC 1323)。(对普通地百M网络而言,关闭会降低开销,所以如果不是高速网络,可以考虑设置为0)

    net.ipv4.tcp_sack = 1
    缺省值为1
    使用 Selective ACK﹐它可以用来查找特定的遗失的数据报--- 因此有助于快速恢复状态。该文件表示是否启用有选择的应答(Selective Acknowledgment),这可以通过有选择地应答乱序接收到的报文来提高性能(这样可以让发送者只发送丢失的报文段)。(对于广域网通信来说这个选项应该启用,但是这会增加对 CPU 的占用。)

    net.ipv4.tcp_retrans_collapse = 1
    缺省值为1
    对于某些有bug的打印机提供针对其bug的兼容性。(一般不需要这个支持,可以关闭它)

    net.ipv4.ip_default_ttl = 64
    net.ipv4.ip_nonlocal_bind = 0
    net.ipv4.tcp_syn_retries = 5
    对于一个新建连接,内核要发送多少个 SYN 连接请求才决定放弃。不应该大于255,默认值是5,对应于180秒左右时间。(对于大负载而物理通信良好的网络而言,这个值偏高,可修改为2.这个值仅仅是针对对外的连接,对进来的连接,是由tcp_retries1 决定的)

    net.ipv4.tcp_synack_retries = 2
    对于远端的连接请求SYN,内核会发送SYN + ACK数据报,以确认收到上一个 SYN连接请求包。这是所谓的三次握手( threeway handshake)机制的第二个步骤。这里决定内核在放弃连接之前所送出的 SYN+ACK 数目。不应该大于255,默认值是5,对应于180秒左右时间。(可以根据上面的tcp_syn_retries来决定这个值)

    net.ipv4.tcp_max_orphans = 262144
    缺省值是8192
    系统所能处理不属于任何进程的TCP sockets最大数量。假如超过这个数量﹐那么不属于任何进程的连接会被立即reset,并同时显示警告信息。之所以要设定这个限制﹐纯粹为了抵御那些简单的 DoS 攻击﹐千万不要依赖这个或是人为的降低这个限制(这个值Redhat AS版本中设置为32768,但是很多防火墙修改的时候,建议该值修改为2000)

    net.ipv4.tcp_max_tw_buckets = 5000
    默认值是180000
    系统在同时所处理的最大 timewait sockets 数目。如果超过此数的话﹐time-wait socket 会被立即砍除并且显示警告信息。之所以要设定这个限制﹐纯粹为了抵御那些简单的 DoS 攻击﹐千万不要人为的降低这个限制﹐不过﹐如果网络条件需要比默认值更多﹐则可以提高它(或许还要增加内存)。(事实上做NAT的时候最好可以适当地增加该值)

    net.ipv4.ip_dynaddr = 0
    net.ipv4.tcp_keepalive_time = 7200
    当keepalive打开的情况下,TCP发送keepalive消息的频率。(由于目前网络攻击等因素,造成了利用这个进行的攻击很频繁,曾经也有cu的朋友提到过,说如果2边建立了连接,然后不发送任何数据或者rst/fin消息,那么持续的时间是不是就是2小时,空连接攻击?tcp_keepalive_time就是预防此情形的.我个人在做nat服务的时候的修改值为1800秒)

    net.ipv4.tcp_keepalive_probes = 9
    TCP发送keepalive探测以确定该连接已经断开的次数。(注意:保持连接仅在SO_KEEPALIVE套接字选项被打开是才发送.次数默认不需要修改,当然根据情形也可以适当地缩短此值.设置为5比较合适)

    net.ipv4.tcp_keepalive_intvl = 75
    探测消息发送的频率,乘以tcp_keepalive_probes就得到对于从开始探测以来没有响应的连接杀除的时间。默认值为75秒,也就是没有活动的连接将在大约11分钟以后将被丢弃。(对于普通应用来说,这个值有一些偏大,可以根据需要改小.特别是web类服务器需要改小该值,15是个比较合适的值)

    net.ipv4.tcp_retries1 = 3
    放弃回应一个TCP连接请求前﹐需要进行多少次重试。RFC 规定最低的数值是3﹐这也是默认值﹐根据RTO的值大约在3秒 - 8分钟之间。(注意:这个值同时还决定进入的syn连接)

    net.ipv4.tcp_retries2 = 15
    在丢弃激活(已建立通讯状况)的TCP连接之前﹐需要进行多少次重试。默认值为15,根据RTO的值来决定,相当于13-30分钟(RFC1122规定,必须大于100秒).(这个值根据目前的网络设置,可以适当地改小,我的网络内修改为了5)

    net.ipv4.tcp_fin_timeout = 60
    net.ipv4.tcp_syncookies = 1
    默认值是0
    只有在内核编译时选择了CONFIG_SYNCOOKIES时才会发生作用。当出现syn等候队列出现溢出时象对方发送syncookies。目的是为了防止syn flood攻击。
    注意:该选项千万不能用于那些没有收到攻击的高负载服务器,如果在日志中出现synflood消息,但是调查发现没有收到synflood攻击,而是合法用户的连接负载过高的原因,你应该调整其它参数来提高服务器性能。参考:
    tcp_max_syn_backlog
    tcp_synack_retries
    tcp_abort_on_overflow
    syncookie严重的违背TCP协议,不允许使用TCP扩展,可能对某些服务导致严重的性能影响(如SMTP转发)。(注意,该实现与BSD上面使用的tcp proxy一样,是违反了RFC中关于tcp连接的三次握手实现的,但是对于防御syn-flood的确很有用.)

    net.ipv4.tcp_tw_recycle = 0
    默认值是0
    打开快速 TIME-WAIT sockets 回收。除非得到技术专家的建议或要求﹐请不要随意修改这个值。(做NAT的时候,建议打开它)

    net.ipv4.tcp_abort_on_overflow = 0
    缺省值是0
    当守护进程太忙而不能接受新的连接,就象对方发送reset消息,默认值是false。这意味着当溢出的原因是因为一个偶然的猝发,那么连接将恢复状态。只有在你确信守护进程真的不能完成连接请求时才打开该选项,该选项会影响客户的使用。(对待已经满载的sendmail,apache这类服务的时候,这个可以很快让客户端终止连接,可以给予服务程序处理已有连接的缓冲机会,所以很多防火墙上推荐打开它)

    net.ipv4.tcp_stdurg = 0
    默认值为0
    使用 TCP urg pointer 字段中的主机请求解释功能。大部份的主机都使用老旧的 BSD解释,因此如果您在 Linux 打开它﹐或会导致不能和它们正确沟通。

    net.ipv4.tcp_rfc1337 = 0
    缺省值为0
    这个开关可以启动对于在RFC1337中描述的"tcp 的time-wait暗杀危机"问题的修复。启用后,内核将丢弃那些发往time-wait状态TCP套接字的RST 包.

    net.ipv4.tcp_max_syn_backlog = 1024
    对于那些依然还未获得客户端确认的连接请求﹐需要保存在队列中最大数目。对于超过 128Mb 内存的系统﹐默认值是1024 ﹐低于 128Mb 的则为 128。如果服务器经常出现过载﹐可以尝试增加这个数字。警告﹗假如您将此值设为大于1024﹐最好修改 include/net/tcp.h 里面的 TCP_SYNQ_HSIZE ﹐以保持TCP_SYNQ_HSIZE*16<=tcp_max_syn_backlog ﹐并且编进核心之内。(SYN Flood攻击利用TCP协议散布握手的缺陷,伪造虚假源IP地址发送大量TCP-SYN半打开连接到目标系统,最终导致目标系统Socket队列资源耗尽而无法接受新的连接。为了应付这种攻击,现代Unix系统中普遍采用多连接队列处理的方式来缓冲(而不是解决)这种攻击,是用一个基本队列处理正常的完全连接应用(Connect()和Accept() ),是用另一个队列单独存放半打开连接。这种双队列处理方式和其他一些系统内核措施(例如Syn-Cookies/Caches)联合应用时,能够比较有效的缓解小规模的SYN Flood攻击(事实证明<1000p/s)加大SYN队列长度可以容纳更多等待连接的网络连接数,所以对Server来说可以考虑增大该值.)

    net.ipv4.ip_local_port_range = 32768    61000
    net.ipv4.ip_local_reserved_ports =
    net.ipv4.igmp_max_memberships = 20
    net.ipv4.igmp_max_msf = 10
    net.ipv4.inet_peer_threshold = 65664
    net.ipv4.inet_peer_minttl = 120
    net.ipv4.inet_peer_maxttl = 600
    net.ipv4.inet_peer_gc_mintime = 10
    net.ipv4.inet_peer_gc_maxtime = 120
    net.ipv4.tcp_orphan_retries = 0
    在近端丢弃TCP连接之前﹐要进行多少次重试。默认值是7个﹐相当于 50秒 - 16分钟﹐视 RTO 而定。如果您的系统是负载很大的web服务器﹐那么也许需要降低该值﹐这类 sockets 可能会耗费大量的资源。另外参的考tcp_max_orphans 。(事实上做NAT的时候,降低该值也是好处显著的,我本人的网络环境中降低该值为3)

    net.ipv4.tcp_fack = 1
    缺省值为1
    打开FACK拥塞避免和快速重传功能。(注意,当tcp_sack设置为0的时候,这个值即使设置为1也无效)

    net.ipv4.tcp_reordering = 3
    默认值是3
    TCP流中重排序的数据报最大数量 。 (一般有看到推荐把这个数值略微调整大一些,比如5)

    net.ipv4.tcp_ecn = 2
    缺省值为0
    打开TCP的直接拥塞通告功能。

    net.ipv4.tcp_dsack = 1
    缺省值为1
    允许TCP发送"两个完全相同"的SACK。

    net.ipv4.tcp_mem = 753600    1004800    1507200
    tcp_mem(3个INTEGER变量):low, pressure, high
    low:当TCP使用了低于该值的内存页面数时,TCP不会考虑释放内存。(理想情况下,这个值应与指定给 tcp_wmem 的第 2 个值相匹配 - 这第 2 个值表明,最大页面大小乘以最大并发请求数除以页大小 (131072 * 300 / 4096)。 )
    pressure:当TCP使用了超过该值的内存页面数量时,TCP试图稳定其内存使用,进入pressure模式,当内存消耗低于low值时则退出pressure状态。(理想情况下这个值应该是 TCP 可以使用的总缓冲区大小的最大值 (204800 * 300 / 4096)。 )
    high:允许所有tcp sockets用于排队缓冲数据报的页面量。(如果超过这个值,TCP 连接将被拒绝,这就是为什么不要令其过于保守 (512000 * 300 / 4096) 的原因了。 在这种情况下,提供的价值很大,它能处理很多连接,是所预期的 2.5 倍;或者使现有连接能够传输 2.5 倍的数据。 我的网络里为192000 300000 732000)
    一般情况下这些值是在系统启动时根据系统内存数量计算得到的。

    net.ipv4.tcp_wmem = 4096    16384    4194304
    tcp_wmem(3个INTEGER变量): min, default, max
    min:为TCP socket预留用于发送缓冲的内存最小值。每个tcp socket都可以在建议以后都可以使用它。默认值为4096(4K)。
    default:为TCP socket预留用于发送缓冲的内存数量,默认情况下该值会影响其它协议使用的net.core.wmem_default 值,一般要低于net.core.wmem_default的值。默认值为16384(16K)。
    max: 用于TCP socket发送缓冲的内存最大值。该值不会影响net.core.wmem_max,"静态"选择参数SO_SNDBUF则不受该值影响。默认值为131072(128K)。(对于服务器而言,增加这个参数的值对于发送数据很有帮助,在我的网络环境中,修改为了51200 131072 204800)

    net.ipv4.tcp_rmem = 4096    87380    4194304
    cp_rmem (3个INTEGER变量): min, default, max
    min:为TCP socket预留用于接收缓冲的内存数量,即使在内存出现紧张情况下tcp socket都至少会有这么多数量的内存用于接收缓冲,默认值为8K。
    default:为TCP socket预留用于接收缓冲的内存数量,默认情况下该值影响其它协议使用的net.core.wmem_default 值。该值决定了在tcp_adv_win_scale、tcp_app_win和tcp_app_win=0默认值情况下,TCP窗口大小为65535。默认值为87380
    max:用于TCP socket接收缓冲的内存最大值。该值不会影响 net.core.wmem_max,"静态"选择参数 SO_SNDBUF则不受该值影响。默认值为 128K。默认值为87380*2 bytes。(可以看出,.max的设置最好是default的两倍,对于NAT来说主要该增加它,我的网络里为 51200 131072 204800)

    net.ipv4.tcp_app_win = 31
    默认值是31
    保留max(window/2^tcp_app_win, mss)数量的窗口由于应用缓冲。当为0时表示不需要缓冲。

    net.ipv4.tcp_adv_win_scale = 2
    默认值为2
    计算缓冲开销bytes/2^tcp_adv_win_scale(如果tcp_adv_win_scale > 0)或者bytes-bytes/2^(-tcp_adv_win_scale)(如果tcp_adv_win_scale <= 0)。
    net.ipv4.tcp_tw_reuse = 0

    默认值是0
    该文件表示是否允许重新应用处于TIME-WAIT状态的socket用于新的TCP连接(这个对快速重启动某些服务,而启动后提示端口已经被使用的情形非常有帮助)

    net.ipv4.tcp_frto = 2
    net.ipv4.tcp_frto_response = 0
    net.ipv4.tcp_low_latency = 0
    缺省值为0
    允许 TCP/IP 栈适应在高吞吐量情况下低延时的情况;这个选项一般情形是的禁用。(但在构建Beowulf 集群的时候,打开它很有帮助)

    net.ipv4.tcp_no_metrics_save = 0
    net.ipv4.tcp_moderate_rcvbuf = 1
    net.ipv4.tcp_tso_win_divisor = 3
    net.ipv4.tcp_congestion_control = cubic
    net.ipv4.tcp_abc = 0
    net.ipv4.tcp_mtu_probing = 0
    net.ipv4.tcp_base_mss = 512
    net.ipv4.tcp_workaround_signed_windows = 0
    net.ipv4.tcp_challenge_ack_limit = 100
    net.ipv4.tcp_limit_output_bytes = 262144
    net.ipv4.tcp_dma_copybreak = 4096
    net.ipv4.tcp_slow_start_after_idle = 1
    net.ipv4.cipso_cache_enable = 1
    net.ipv4.cipso_cache_bucket_size = 10
    net.ipv4.cipso_rbm_optfmt = 0
    net.ipv4.cipso_rbm_strictvalid = 1
    net.ipv4.tcp_available_congestion_control = cubic reno
    net.ipv4.tcp_allowed_congestion_control = cubic reno
    net.ipv4.tcp_max_ssthresh = 0
    net.ipv4.tcp_thin_linear_timeouts = 0
    net.ipv4.tcp_thin_dupack = 0
    net.ipv4.tcp_min_tso_segs = 2
    net.ipv4.udp_mem = 753600    1004800    1507200
    net.ipv4.udp_rmem_min = 4096
    net.ipv4.udp_wmem_min = 4096
    net.ipv4.conf.all.forwarding = 0
    net.ipv4.conf.all.mc_forwarding = 0
    net.ipv4.conf.all.accept_redirects = 1
    net.ipv4.conf.all.secure_redirects = 1
    net.ipv4.conf.all.shared_media = 1
    net.ipv4.conf.all.rp_filter = 0
    net.ipv4.conf.all.send_redirects = 1
    net.ipv4.conf.all.accept_source_route = 0
    net.ipv4.conf.all.src_valid_mark = 0
    net.ipv4.conf.all.proxy_arp = 0
    net.ipv4.conf.all.medium_id = 0
    net.ipv4.conf.all.bootp_relay = 0
    net.ipv4.conf.all.log_martians = 0
    net.ipv4.conf.all.tag = 0
    net.ipv4.conf.all.arp_filter = 0
    net.ipv4.conf.all.arp_announce = 2
    net.ipv4.conf.all.arp_ignore = 0
    net.ipv4.conf.all.arp_accept = 0
    net.ipv4.conf.all.arp_notify = 0
    net.ipv4.conf.all.proxy_arp_pvlan = 0
    net.ipv4.conf.all.disable_xfrm = 0
    net.ipv4.conf.all.disable_policy = 0
    net.ipv4.conf.all.force_igmp_version = 0
    net.ipv4.conf.all.promote_secondaries = 0
    net.ipv4.conf.all.accept_local = 0
    net.ipv4.conf.all.route_localnet = 0
    net.ipv4.conf.default.forwarding = 0
    net.ipv4.conf.default.mc_forwarding = 0
    net.ipv4.conf.default.accept_redirects = 1
    net.ipv4.conf.default.secure_redirects = 1
    net.ipv4.conf.default.shared_media = 1
    net.ipv4.conf.default.rp_filter = 0
    net.ipv4.conf.default.send_redirects = 1
    net.ipv4.conf.default.accept_source_route = 0
    net.ipv4.conf.default.src_valid_mark = 0
    net.ipv4.conf.default.proxy_arp = 0
    net.ipv4.conf.default.medium_id = 0
    net.ipv4.conf.default.bootp_relay = 0
    net.ipv4.conf.default.log_martians = 0
    net.ipv4.conf.default.tag = 0
    net.ipv4.conf.default.arp_filter = 0
    net.ipv4.conf.default.arp_announce = 2
    net.ipv4.conf.default.arp_ignore = 0
    net.ipv4.conf.default.arp_accept = 0
    net.ipv4.conf.default.arp_notify = 0
    net.ipv4.conf.default.proxy_arp_pvlan = 0
    net.ipv4.conf.default.disable_xfrm = 0
    net.ipv4.conf.default.disable_policy = 0
    net.ipv4.conf.default.force_igmp_version = 0
    net.ipv4.conf.default.promote_secondaries = 0
    net.ipv4.conf.default.accept_local = 0
    net.ipv4.conf.default.route_localnet = 0
    net.ipv4.conf.lo.forwarding = 0
    net.ipv4.conf.lo.mc_forwarding = 0
    net.ipv4.conf.lo.accept_redirects = 1
    net.ipv4.conf.lo.secure_redirects = 1
    net.ipv4.conf.lo.shared_media = 1
    net.ipv4.conf.lo.rp_filter = 0
    net.ipv4.conf.lo.send_redirects = 1
    net.ipv4.conf.lo.accept_source_route = 1
    net.ipv4.conf.lo.src_valid_mark = 0
    net.ipv4.conf.lo.proxy_arp = 0
    net.ipv4.conf.lo.medium_id = 0
    net.ipv4.conf.lo.bootp_relay = 0
    net.ipv4.conf.lo.log_martians = 0
    net.ipv4.conf.lo.tag = 0
    net.ipv4.conf.lo.arp_filter = 0
    net.ipv4.conf.lo.arp_announce = 2
    net.ipv4.conf.lo.arp_ignore = 0
    net.ipv4.conf.lo.arp_accept = 0
    net.ipv4.conf.lo.arp_notify = 0
    net.ipv4.conf.lo.proxy_arp_pvlan = 0
    net.ipv4.conf.lo.disable_xfrm = 1
    net.ipv4.conf.lo.disable_policy = 1
    net.ipv4.conf.lo.force_igmp_version = 0
    net.ipv4.conf.lo.promote_secondaries = 0
    net.ipv4.conf.lo.accept_local = 0
    net.ipv4.conf.lo.route_localnet = 0
    net.ipv4.conf.eth0.forwarding = 0
    net.ipv4.conf.eth0.mc_forwarding = 0
    net.ipv4.conf.eth0.accept_redirects = 1
    net.ipv4.conf.eth0.secure_redirects = 1
    net.ipv4.conf.eth0.shared_media = 1
    net.ipv4.conf.eth0.rp_filter = 0
    net.ipv4.conf.eth0.send_redirects = 1
    net.ipv4.conf.eth0.accept_source_route = 0
    net.ipv4.conf.eth0.src_valid_mark = 0
    net.ipv4.conf.eth0.proxy_arp = 0
    net.ipv4.conf.eth0.medium_id = 0
    net.ipv4.conf.eth0.bootp_relay = 0
    net.ipv4.conf.eth0.log_martians = 0
    net.ipv4.conf.eth0.tag = 0
    net.ipv4.conf.eth0.arp_filter = 0
    net.ipv4.conf.eth0.arp_announce = 2
    net.ipv4.conf.eth0.arp_ignore = 0
    net.ipv4.conf.eth0.arp_accept = 0
    net.ipv4.conf.eth0.arp_notify = 0
    net.ipv4.conf.eth0.proxy_arp_pvlan = 0
    net.ipv4.conf.eth0.disable_xfrm = 0
    net.ipv4.conf.eth0.disable_policy = 0
    net.ipv4.conf.eth0.force_igmp_version = 0
    net.ipv4.conf.eth0.promote_secondaries = 0
    net.ipv4.conf.eth0.accept_local = 0
    net.ipv4.conf.eth0.route_localnet = 0
    net.ipv4.ip_forward = 0
    net.ipv4.xfrm4_gc_thresh = 2097152
    net.ipv4.ipfrag_high_thresh = 4194304
    net.ipv4.ipfrag_low_thresh = 3145728
    net.ipv4.ipfrag_time = 30
    net.ipv4.icmp_echo_ignore_all = 0
    net.ipv4.icmp_echo_ignore_broadcasts = 1
    net.ipv4.icmp_ignore_bogus_error_responses = 1
    net.ipv4.icmp_errors_use_inbound_ifaddr = 0
    net.ipv4.icmp_ratelimit = 1000
    net.ipv4.icmp_ratemask = 6168
    net.ipv4.rt_cache_rebuild_count = 4
    net.ipv4.ping_group_range = 1    0
    net.ipv4.ip_no_pmtu_disc = 0
    net.ipv4.ip_forward_use_pmtu = 0
    net.ipv4.ipfrag_secret_interval = 600
    net.ipv4.ipfrag_max_dist = 64
    net.unix.max_dgram_qlen = 10
    abi.vsyscall32 = 1
    crypto.fips_enabled = 0
    sunrpc.rpc_debug = 0
    sunrpc.nfs_debug = 0
    sunrpc.nfsd_debug = 0
    sunrpc.nlm_debug = 0
    sunrpc.transports = tcp 1048576
    sunrpc.transports = udp 32768
    sunrpc.transports = tcp-bc 1048576
    sunrpc.udp_slot_table_entries = 16
    sunrpc.tcp_slot_table_entries = 2
    sunrpc.tcp_max_slot_table_entries = 65536
    sunrpc.min_resvport = 665
    sunrpc.max_resvport = 1023
    sunrpc.tcp_fin_timeout = 15
    默认值是 60
    对于本端断开的socket连接,TCP保持在FIN-WAIT-2状态的时间。对方可能会断开连接或一直不结束连接或不可预料的进程死亡。默认值为 60 秒。过去在2.2版本的内核中是 180 秒。您可以设置该值﹐但需要注意﹐如果您的机器为负载很重的web服务器﹐您可能要冒内存被大量无效数据报填满的风险﹐FIN-WAIT-2 sockets 的危险性低于 FIN-WAIT-1 ﹐因为它们最多只吃 1.5K 的内存﹐但是它们存在时间更长。另外参考 tcp_max_orphans。(事实上做NAT的时候,降低该值也是好处显著的,我本人的网络环境中降低该值为30)


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  • 原文地址:https://www.cnblogs.com/lmgsanm/p/8664137.html
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