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tech:memoire_linux

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Les deux révisions précédentesRévision précédente
Prochaine révision		Révision précédente
tech:memoire_linux [2026/08/03 17:35] – Jean-Baptistetech:memoire_linux [2026/09/18 10:19] (Version actuelle) – Jean-Baptiste
Ligne 6: Ligne 6:
 Voir : Voir :
 * [[Supervision - sonde Nagios - Memoire Linux]] * [[Supervision - sonde Nagios - Memoire Linux]]
 +* psacct [[Suivre la conso CPU par utilisateurs]]
 * https://linuxblog.io/free-vs-available-memory-in-linux/ * https://linuxblog.io/free-vs-available-memory-in-linux/
 * https://en.pingcap.com/blog/linux-kernel-vs-memory-fragmentation-2/ * https://en.pingcap.com/blog/linux-kernel-vs-memory-fragmentation-2/
Ligne 177: Ligne 178:
             - memCached // free = total - used             - memCached // free = total - used
 ~~~ ~~~
 +
 +
  
 ## Exemple ## Exemple
  
 +Voir psacct [[Suivre la conso CPU par utilisateurs]]
  
 ~~~bash ~~~bash
 free -mt free -mt
 +ps aux --sort=-%mem | head -n 11
 vmstat -SM 45 10 vmstat -SM 45 10
 vmstat -SM -a 45 10 vmstat -SM -a 45 10
Ligne 191: Ligne 196:
 ps -eo comm,pcpu,pmem,rss --sort rss | tail -n 30 | tac ps -eo comm,pcpu,pmem,rss --sort rss | tail -n 30 | tac
 ~~~ ~~~
 +
 +
  
 ~~~bash ~~~bash
Ligne 292: Ligne 299:
  
 OOM OOM
 +~~~bash
 echo -1000 > /proc/self/oom_score_adj echo -1000 > /proc/self/oom_score_adj
  
 cat /proc/<pid>/oom_score cat /proc/<pid>/oom_score
 echo -1000 > /proc/<pid>/oom_score_adj # protect from OOM kill echo -1000 > /proc/<pid>/oom_score_adj # protect from OOM kill
 +~~~
  
 Or in a specific cgroup, set oom_kill_disable to 1. Or in a specific cgroup, set oom_kill_disable to 1.
 +~~~bash
 echo 1000 > /proc/<pid>/oom_score_adj # mark as first target echo 1000 > /proc/<pid>/oom_score_adj # mark as first target
 +~~~
  
-For systemd services, use OOMScoreAdjust=-1000 in the unit file to protect critical processes. +For systemd services, use `OOMScoreAdjust=-1000` in the unit file to protect critical processes. 
-cgroup_enable=memory swapaccount=1+`cgroup_enable=memory swapaccount=1` 
 + 
 +~~~
 $ echo $(($(cat /sys/fs/cgroup/memory/memory.max_usage_in_bytes) / 2**20)) MB $ echo $(($(cat /sys/fs/cgroup/memory/memory.max_usage_in_bytes) / 2**20)) MB
 11389 MB 11389 MB
 $ cat /sys/fs/cgroup/memory/memory.stat $ cat /sys/fs/cgroup/memory/memory.stat
 +~~~
 +
 ---- ----
  
Ligne 312: Ligne 326:
 TLB hit TLB miss TLB hit TLB miss
  
 +~~~bash
 sudo perf stat -e dTLB-loads,dTLB-load-misses,iTLB-loads,iTLB-load-misses -a sleep 60 sudo perf stat -e dTLB-loads,dTLB-load-misses,iTLB-loads,iTLB-load-misses -a sleep 60
- 
  
 perf list | grep -i tlb perf list | grep -i tlb
-Slub+~~~
  
 +Slub
 +~~~bash
 slabtop --sort=1 slabtop --sort=1
 +~~~
  
 +~~~bash
 slabinfo -v slabinfo -v
 +~~~
 +
 access.redhat.com/ access.redhat.com/
 page_owner=on page_owner=on
-Premature swapping while there is still plenty of pagecache to be reclaimed  
-Cgroup v1 
-https://access.redhat.com/solutions/6785021 
  
-https://fatdba.com/2025/12/12/when-linux-swaps-away-my-sleep-mysql-rhel8-and-the-curious-case-of-high-swap-usage/ 
  
-https://docs.couchbase.com/server/current/install/install-swap-space.html+## Premature swapping while there is still plenty of pagecache to be reclaimed 
  
-https://support.axway.com/kb/192440/language/en +Cgroup v1
- +
-https://communities.sas.com/t5/Administration-and-Deployment/Red-Hat-RHEL-8-Release-Swappiness-Algorithm-Setting-Requires/td-p/921008+
  
-https://docs.acceldata.io/odp/documentation/troubleshooting-premature-swapping+  * https://access.redhat.com/solutions/6785021 
 +  * https://fatdba.com/2025/12/12/when-linux-swaps-away-my-sleep-mysql-rhel8-and-the-curious-case-of-high-swap-usage/ 
 +  * https://docs.couchbase.com/server/current/install/install-swap-space.html 
 +  * https://support.axway.com/kb/192440/language/en 
 +  * https://communities.sas.com/t5/Administration-and-Deployment/Red-Hat-RHEL-8-Release-Swappiness-Algorithm-Setting-Requires/td-p/921008 
 +  * https://docs.acceldata.io/odp/documentation/troubleshooting-premature-swapping 
 +  * [Change in swap behavior between RHEL 7 and RHEL 8 kernels](https://access.redhat.com/solutions/7042476)
  
-Change in swap behavior between RHEL 7 and RHEL 8 kernels  
-https://access.redhat.com/solutions/7042476 
  
tech/memoire_linux.1785771314.txt.gz · Dernière modification : de Jean-Baptiste
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