PHP-FPM Tweaking configuration

See sticky thread at PHP-FPM - How to troubleshoot & optimize PHP-FPM server? with links that reference to all relevant tools and config files to edit

including links to PHP-FPM - WARNING: [pool www] server reached max_children setting (50), consider raising it

Also official site has links to all config files overview for entire Centmin Mod server Centmin Mod Configuration Files - CentminMod.com LEMP Nginx web stack for CentOS. Under PHP-FPM section

 

that is for php.ini settings but not for php-fpm configuration settings which uses different file as outlined at Centmin Mod Configuration Files - CentminMod.com LEMP Nginx web stack for CentOS

official site has links to all config files overview for entire Centmin Mod server Centmin Mod Configuration Files - CentminMod.com LEMP Nginx web stack for CentOS. Under PHP-FPM section

 

when you upgrade php via centmin.sh menu option 5, it will prompt if you want to overwrite custom php-fpm.conf file so if you answered yes, then it will. If you don't want to overwrite answer no. You can also disable the prompt to overwrite if you always answer no anyway via adding to your persistent config file /etc/centminmod/custom_config.inc the setting

Code (Text):

PHP_OVERWRITECONF='n'

 

404 not found errors are normal if someone/bot/crawler scans or visitors paths not found on your server. If you use Cloudflare you custom what 404 queried paths can be blocked at Cloudflare Firewall level. I do this on forum for any wordpress related paths that crawlers try to scan/poke at on the forums as there should be no wordpress paths on my forums.

speed can be relative and usually related to php-fpm service part - more php-fpm children, then potentially longer to restart especially if php-fpm children are actively doing work.

 

discussed at PHP-FPM - WARNING: [pool www] server reached max_children setting (50), consider raising it too

basically you need to keep an optimal pm.max_children to cpu thread ratio based on your monitored usage profiles for your web apps. In other words if you don't have enough cpu threads available, then raising pm.max_children too high will slow php response times and increase cpu usage

example excerpt output from Centmin Mod's cminfo phpstats output for 48 cpu thread based server

Code (Text):

lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                48
On-line CPU(s) list:   0-47
Thread(s) per core:    2
Core(s) per socket:    12
Socket(s):             2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 85
Model name:            Intel(R) Xeon(R) Silver 4116 CPU @ 2.10GHz
Stepping:              4
CPU MHz:               2100.000
CPU max MHz:           3000.0000
CPU min MHz:           800.0000
BogoMIPS:              4200.00
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              1024K
L3 cache:              16896K
NUMA node0 CPU(s):     0-11,24-35
NUMA node1 CPU(s):     12-23,36-47
Flags:                 fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch epb cat_l3 cdp_l3 invpcid_single intel_ppin intel_pt ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts pku ospke md_clear spec_ctrl intel_stibp flush_l1d

actual max php children to cpu ratio = 160:48 = 3.33:1

Code (Text):

cminfo phpstats

------------------------------------------------------------------
Total PHP-FPM Master Processes: 1
PHP-FPM Pool Names:
www
------------------------------------------------------------------
 40179 php-fpm: master /usr/local/etc/php-fpm.conf
------------------------------------------------------------------
Current Free Memory (KB): 175901204
PHP-FPM Available Memory (KB): 187726924
Estimated Max PHP Children: 2539.91
Estimated Max PHP Children To CPU Thread Ratio: 52.9149
PHP-FPM Total Children: 160 from 1 PHP-FPM master(s)
PHP-FPM Total Used Memory (KB): swap:0 uss:8776660 pss:8795459 rss:11825720
PHP-FPM Average Per Child (KB): swap:0 uss:54854.1 pss:54971.6 rss:73910.8
uss = user set size
pss = process set size
rss = resident set size

Processes active: 4, idle: 156, Requests: 624291, slow: 0, Traffic: 39req/sec
pool:                 www
process manager:      static
start time:           08/Apr/2020:00:02:39 +0000
start since:          15659
accepted conn:        624574
listen queue:         0
max listen queue:     1
listen queue len:     1024
idle processes:       154
active processes:     6
total processes:      160
max active processes: 72
max children reached: 0
slow requests:        0