1

I'm running a Ubuntu 14 server with LAMP on virtual cloud hosting (CityCloud).

The server is usually doing very well with response time<0.5s. However, the problems start at peak hours, mainly Monday-Wednesday/Thursday, with response times at around 7-8 seconds or more. These times were more or less halved by passing to worker MPM and php-fpm, thanks to @drew010 over at stackoverflow.

Now, I would like to see if there are any last tweaks I could do to get rid of those remaining 3s of avg load time during busy hours.

According to Google Analytics: The website has got some ~5 million page views per month, and during peak hour some 12-13.000 thousand page views per hour.

Here's my setup:

  • Ubuntu 14.04.3 LTS
  • PHP Version 5.5.9, FPM/FastCGI
  • 4 CPU cores
  • 8 RAM
  • Limited to 1 Gbps bandwidth and 1 TB transfer/month
  • < 6% CPU usage during peak hours
  • Memory used < 2GB
  • ~2M txbps during peak hours
  • Static content is served from a separate subdomain (same machine) with expires headers "access plus 1 month".
  • MySQL running on the same machine.
  • MySQL queries have been measured to be fast and not an issue.

Obviously, 4 cores/8 RAM is excessive. My intentions are to fall back to at most 2 cores/4 RAM, if performance is good.

This is a netstat output during peak hour:

$ netstat -ant | awk '{print $6}' | sort | uniq -c | sort -n
      3 CLOSING
      5 LISTEN
      8 FIN_WAIT1
     69 LAST_ACK
     80 SYN_RECV
    117 ESTABLISHED
    147 FIN_WAIT2
   1028 TIME_WAIT

Some server-info:

In file: /etc/apache2/mods-enabled/mpm_worker.conf
  13: StartServers 2
  14: MinSpareThreads 25
  15: MaxSpareThreads 75
  16: ThreadLimit 64
  17: ThreadsPerChild 25
  18: MaxRequestWorkers 150

Some kernel option values:

/proc/sys/net/core/somaxconn: 128
/proc/sys/net/core/netdev_max_backlog: 1000
/proc/sys/net/ipv4/tcp_max_syn_backlog: 256
/proc/sys/net/ipv4/ip_local_port_range: 32768   61000

MySQL "SHOW GLOBAL STATUS":

Aborted_clients 7
Aborted_connects    14
Binlog_cache_disk_use   0
Binlog_cache_use    0
Binlog_stmt_cache_disk_use  0
Binlog_stmt_cache_use   0
Bytes_received  7324492238
Bytes_sent  33143229342
Com_admin_commands  0
Com_assign_to_keycache  0
Com_alter_db    0
Com_alter_db_upgrade    0
Com_alter_event 0
Com_alter_function  0
Com_alter_procedure 0
Com_alter_server    0
Com_alter_table 2
Com_alter_tablespace    0
Com_analyze 0
Com_begin   0
Com_binlog  0
Com_call_procedure  0
Com_change_db   1277679
Com_change_master   0
Com_check   0
Com_checksum    0
Com_commit  0
Com_create_db   0
Com_create_event    0
Com_create_function 0
Com_create_index    0
Com_create_procedure    0
Com_create_server   0
Com_create_table    0
Com_create_trigger  0
Com_create_udf  0
Com_create_user 0
Com_create_view 0
Com_dealloc_sql 0
Com_delete  19
Com_delete_multi    0
Com_do  0
Com_drop_db 0
Com_drop_event  0
Com_drop_function   0
Com_drop_index  0
Com_drop_procedure  0
Com_drop_server 0
Com_drop_table  0
Com_drop_trigger    0
Com_drop_user   0
Com_drop_view   0
Com_empty_query 0
Com_execute_sql 0
Com_flush   0
Com_grant   0
Com_ha_close    0
Com_ha_open 0
Com_ha_read 0
Com_help    0
Com_insert  1301
Com_insert_select   0
Com_install_plugin  0
Com_kill    0
Com_load    0
Com_lock_tables 18
Com_optimize    1
Com_preload_keys    0
Com_prepare_sql 0
Com_purge   0
Com_purge_before_date   0
Com_release_savepoint   0
Com_rename_table    0
Com_rename_user 0
Com_repair  0
Com_replace 7
Com_replace_select  0
Com_reset   0
Com_resignal    0
Com_revoke  0
Com_revoke_all  0
Com_rollback    0
Com_rollback_to_savepoint   0
Com_savepoint   0
Com_select  8939751
Com_set_option  2555998
Com_signal  0
Com_show_authors    0
Com_show_binlog_events  0
Com_show_binlogs    94
Com_show_charsets   0
Com_show_collations 0
Com_show_contributors   0
Com_show_create_db  18
Com_show_create_event   0
Com_show_create_func    0
Com_show_create_proc    0
Com_show_create_table   356
Com_show_create_trigger 0
Com_show_databases  28
Com_show_engine_logs    0
Com_show_engine_mutex   0
Com_show_engine_status  0
Com_show_events 5
Com_show_errors 0
Com_show_fields 381
Com_show_function_status    5
Com_show_grants 5
Com_show_keys   40
Com_show_master_status  43
Com_show_open_tables    0
Com_show_plugins    0
Com_show_privileges 0
Com_show_procedure_status   5
Com_show_processlist    1099
Com_show_profile    0
Com_show_profiles   0
Com_show_relaylog_events    0
Com_show_slave_hosts    0
Com_show_slave_status   1118
Com_show_status 1120
Com_show_storage_engines    0
Com_show_table_status   366
Com_show_tables 77
Com_show_triggers   324
Com_show_variables  1135
Com_show_warnings   0
Com_slave_start 0
Com_slave_stop  0
Com_stmt_close  0
Com_stmt_execute    0
Com_stmt_fetch  0
Com_stmt_prepare    0
Com_stmt_reprepare  0
Com_stmt_reset  0
Com_stmt_send_long_data 0
Com_truncate    0
Com_uninstall_plugin    0
Com_unlock_tables   18
Com_update  41612
Com_update_multi    0
Com_xa_commit   0
Com_xa_end  0
Com_xa_prepare  0
Com_xa_recover  0
Com_xa_rollback 0
Com_xa_start    0
Compression OFF
Connections 1277451
Created_tmp_disk_tables 731
Created_tmp_files   9
Created_tmp_tables  3602
Delayed_errors  0
Delayed_insert_threads  0
Delayed_writes  0
Flush_commands  1
Handler_commit  284
Handler_delete  19
Handler_discover    0
Handler_prepare 0
Handler_read_first  485
Handler_read_key    7814753
Handler_read_last   48790
Handler_read_next   55898210
Handler_read_prev   457247
Handler_read_rnd    223213
Handler_read_rnd_next   4231962515
Handler_rollback    0
Handler_savepoint   0
Handler_savepoint_rollback  0
Handler_update  40888
Handler_write   377375
Innodb_buffer_pool_pages_data   202
Innodb_buffer_pool_bytes_data   3309568
Innodb_buffer_pool_pages_dirty  0
Innodb_buffer_pool_bytes_dirty  0
Innodb_buffer_pool_pages_flushed    37
Innodb_buffer_pool_pages_free   7989
Innodb_buffer_pool_pages_misc   0
Innodb_buffer_pool_pages_total  8191
Innodb_buffer_pool_read_ahead_rnd   0
Innodb_buffer_pool_read_ahead   0
Innodb_buffer_pool_read_ahead_evicted   0
Innodb_buffer_pool_read_requests    2817
Innodb_buffer_pool_reads    196
Innodb_buffer_pool_wait_free    0
Innodb_buffer_pool_write_requests   86
Innodb_data_fsyncs  39
Innodb_data_pending_fsyncs  0
Innodb_data_pending_reads   0
Innodb_data_pending_writes  0
Innodb_data_read    5394432
Innodb_data_reads   206
Innodb_data_writes  67
Innodb_data_written 1235456
Innodb_dblwr_pages_written  37
Innodb_dblwr_writes 9
Innodb_have_atomic_builtins ON
Innodb_log_waits    0
Innodb_log_write_requests   35
Innodb_log_writes   10
Innodb_os_log_fsyncs    21
Innodb_os_log_pending_fsyncs    0
Innodb_os_log_pending_writes    0
Innodb_os_log_written   17408
Innodb_page_size    16384
Innodb_pages_created    7
Innodb_pages_read   195
Innodb_pages_written    37
Innodb_row_lock_current_waits   0
Innodb_row_lock_time    0
Innodb_row_lock_time_avg    0
Innodb_row_lock_time_max    0
Innodb_row_lock_waits   0
Innodb_rows_deleted 0
Innodb_rows_inserted    0
Innodb_rows_read    59
Innodb_rows_updated 7
Innodb_truncated_status_writes  0
Key_blocks_not_flushed  0
Key_blocks_unused   10770
Key_blocks_used 2626
Key_read_requests   167086090
Key_reads   2430
Key_write_requests  376494
Key_writes  303134
Last_query_cost 0
Max_used_connections    8
Not_flushed_delayed_rows    0
Open_files  141
Open_streams    0
Open_table_definitions  73
Open_tables 137
Opened_files    5062
Opened_table_definitions    80
Opened_tables   150
Performance_schema_cond_classes_lost    0
Performance_schema_cond_instances_lost  0
Performance_schema_file_classes_lost    0
Performance_schema_file_handles_lost    0
Performance_schema_file_instances_lost  0
Performance_schema_locker_lost  0
Performance_schema_mutex_classes_lost   0
Performance_schema_mutex_instances_lost 0
Performance_schema_rwlock_classes_lost  0
Performance_schema_rwlock_instances_lost    0
Performance_schema_table_handles_lost   0
Performance_schema_table_instances_lost 0
Performance_schema_thread_classes_lost  0
Performance_schema_thread_instances_lost    0
Prepared_stmt_count 0
Qcache_free_blocks  2242
Qcache_free_memory  7441152
Qcache_hits 68078488
Qcache_inserts  8868017
Qcache_lowmem_prunes    4451717
Qcache_not_cached   71091
Qcache_queries_in_cache 6797
Qcache_total_blocks 16056
Queries 82178544
Questions   82178543
Rpl_status  AUTH_MASTER
Select_full_join    0
Select_full_range_join  0
Select_range    2041371
Select_range_check  0
Select_scan 1151738
Slave_heartbeat_period  0
Slave_open_temp_tables  0
Slave_received_heartbeats   0
Slave_retried_transactions  0
Slave_running   OFF
Slow_launch_threads 0
Slow_queries    0
Sort_merge_passes   5
Sort_range  878229
Sort_rows   236531
Sort_scan   869
Ssl_accept_renegotiates 0
Ssl_accepts 0
Ssl_callback_cache_hits 0
Ssl_cipher  
Ssl_cipher_list 
Ssl_client_connects 0
Ssl_connect_renegotiates    0
Ssl_ctx_verify_depth    0
Ssl_ctx_verify_mode 0
Ssl_default_timeout 0
Ssl_finished_accepts    0
Ssl_finished_connects   0
Ssl_session_cache_hits  0
Ssl_session_cache_misses    0
Ssl_session_cache_mode  NONE
Ssl_session_cache_overflows 0
Ssl_session_cache_size  0
Ssl_session_cache_timeouts  0
Ssl_sessions_reused 0
Ssl_used_session_cache_entries  0
Ssl_verify_depth    0
Ssl_verify_mode 0
Ssl_version 
Table_locks_immediate   9116984
Table_locks_waited  178
Tc_log_max_pages_used   0
Tc_log_page_size    0
Tc_log_page_waits   0
Threads_cached  6
Threads_connected   2
Threads_created 8
Threads_running 1
Uptime  423398
Uptime_since_flush_status   423398

iostat executed during peak hour:

$ iostat -xdk 1
Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    4.00    0.00    4.00   4.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    2.00     0.00     8.00     8.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00   17.00     0.00    96.00    11.29     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    34.00    0.00    3.00     0.00   152.00   101.33     0.00    1.33    0.00    1.33   1.33   0.40
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    1.00     0.00    12.00    24.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   20.00     0.00   152.00    15.20     0.02    1.20    0.00    1.20   0.60   1.20
vda               0.00    44.00    0.00    2.00     0.00   188.00   188.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    2.00     0.00     8.00     8.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    4.00    0.00    4.00   4.00   0.40
vda               0.00    74.00    0.00  146.00     0.00   908.00    12.44     0.30    2.08    0.00    2.08   0.05   0.80
vda               0.00    46.00    0.00    3.00     0.00   200.00   133.33     0.00    1.33    0.00    1.33   1.33   0.40
vda               0.00     0.00    0.00    4.00     0.00    16.00     8.00     0.00    1.00    0.00    1.00   1.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   20.00     0.00   232.00    23.20     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    41.00    0.00    2.00     0.00   176.00   176.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   17.82     0.00   118.81    13.33     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    42.00    0.00    4.00     0.00   188.00    94.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   12.00     0.00    60.00    10.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    39.00    0.00    2.00     0.00   168.00   168.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   16.00     0.00    76.00     9.50     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    32.00    0.00    2.00     0.00   140.00   140.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   18.00     0.00   100.00    11.11     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    30.00    0.00    2.00     0.00   132.00   132.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   12.00     0.00    48.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    37.00    0.00    3.00     0.00   164.00   109.33     0.01    2.67    0.00    2.67   2.67   0.80
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    48.00    0.00  130.00     0.00   744.00    11.45     0.24    1.88    0.00    1.88   0.06   0.80
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    35.00    0.00    4.00     0.00   160.00    80.00     0.00    1.00    0.00    1.00   1.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   19.00     0.00   172.00    18.11     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    4.00    0.00    4.00   4.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    39.00    0.00    2.00     0.00   168.00   168.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   25.00     0.00   184.00    14.72     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    48.00    0.00    2.00     0.00   204.00   204.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   18.00     0.00   104.00    11.56     0.00    0.22    0.00    0.22   0.22   0.40
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.02   24.00    0.00   24.00  24.00   2.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    39.00    0.00    4.00     0.00   176.00    88.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    1.00     0.00     4.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   17.00     0.00   100.00    11.76     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    38.00    0.00    3.00     0.00   168.00   112.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    2.00     0.00     8.00     8.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   16.00     0.00   100.00    12.50     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    40.00    0.00    2.00     0.00   172.00   172.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00   10.00     0.00    64.00    12.80     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    34.00    0.00    2.00     0.00   144.00   144.00     0.00    2.00    0.00    2.00   2.00   0.40
vda               0.00     0.00    0.00    2.00     0.00    12.00    12.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00    55.00    0.00  117.00     0.00   732.00    12.51     0.28    2.43    0.00    2.43   0.10   1.20
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
vda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00

Any help is appreciated! :-)

  • Can you install sysstat and enable the sar for statistics collection? Also, see with iostat -xdk 1 at the peak period how busy are your block devices. Other thing, post the show global status of your mysql server here for analysis, please! Maybe your mysql are not properly tuned so your VFS and block devices may be doing to much work. – fgbreel Oct 5 '15 at 19:09
  • @fgbreel I've got munin running since last week, is that enough for the statistics part or do you prefer sysstat? – jonr Oct 5 '15 at 19:39
  • both are useful, just see how are the io_wait on system graphs and how busy are your disks on the storage graphs. – fgbreel Oct 5 '15 at 19:53
  • @fgbreel I added the show global status and the iostat -xdk 1 results to the question. As for sysstat/munin, I was going to add some graphs to the question but I need more rep before I can do so... Current values during peak hour at Average latency is Device IO time: 391.32u, IO Wait time: 3.73m, Read IO Wait time: 0.00, Write IO Wait time: 3.73. Device and Write are stable thru 24h, Read has got sporadic peaks independent of peak hours. IO Wait is not visible on the graph. – jonr Oct 6 '15 at 14:12
  • 1
    @fgbreel From your comment, I did some research and finally tweaked: net.core.somaxconn: 128 => 1024, net.core.netdev_max_backlog: 1000 => 65536, net.ipv4.tcp_max_syn_backlog: 256 => 2048. Also in mpm_worker.conf, StartServers 3, MinSpareThreads 75, MaxSpareThreads 250, ThreadLimit 64, ThreadsPerChild 25, MaxRequestWorkers 400. Those remaining peaks have now been removed during busy hours. :-) If you add an answer, I will accept it. – jonr Oct 18 '15 at 11:24
2

You need to increase /proc/sys/net/core/somaxconn. The default is 128. The value should be raised substantially to support bursts of request.

|improve this answer|||||
  • 1
    Not much point in doing that unless you increase Apache listen backlog too. Given the number of connections in TIME_WAIT, you should check net.ipv4.tcp_tw_recycle = 1 and net.ipv4.tcp_tw_reuse = 1. – symcbean Oct 28 '15 at 0:35
  • Well remembered! net.ipv4.tcp_tw_reuse is a good option and less aggressive than net.ipv4.tcp_tw_recycle. Also need to take care with NAT, but is not the case! :D – fgbreel Oct 28 '15 at 13:24

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