{{tag>Mem SNMP}} # Mémoire Linux Voir : * [[Supervision - sonde Nagios - Memoire Linux]] * https://linuxblog.io/free-vs-available-memory-in-linux/ * https://en.pingcap.com/blog/linux-kernel-vs-memory-fragmentation-2/ * /proc/sys/vm/compact_memory * procmap * pmap * smem * lsmem / chmem * https://linuxfr.org/news/sortie-du-noyau-linux-6-17 damon_stat ## Fuite mémoire Voir : * Valgrind * https://www.hebergementwebs.com/tutoriels/linux-recherche-de-fuites-de-memoire-dans-les-programmes * https://qastack.fr/unix/36450/how-can-i-find-a-memory-leak-of-a-running-process * https://www.linuxtricks.fr/wiki/performance-memoire-avec-free-et-vmstat * http://www.ordinateur.cc/syst%C3%A8mes/Linux/205699.html * [Atop - Case study with atop: memory leakage](https://www.atoptool.nl/download/case_leakage.pdf) * https://github.com/iovisor/bcc/blob/master/README.md tools/memleak ## Config ### Kernel Linux param #### NUMA (Non-Uniform Memory Access) Voir : * [What is NUMA ?](https://www.kernel.org/doc/html/v4.19/vm/numa.html) * [La mémoire : numactl, lstopo, perf, etc.](https://www.it-connect.fr/chapitres/la-memoire-numactl-lstopo-perf-etc/) * ''numatop'' Disable NUMA (Pour Oracle DB) /usr/share/doc/kernel-doc-4.18.0/Documentation/x86/x86_64/boot-options.txt ~~~ini numa=off Only set up a single NUMA node spanning all memory. ~~~ Vérif ''numactl'' command can be used to check the status of NUMA ~~~ # numactl -H | grep available available: 8 nodes (0-7) ~~~ ~~~ # numactl -H | grep available available: 2 nodes (0-1) ~~~ If the number of available nodes is ''2 nodes (0-1)'' or ''8 nodes (0-7)'' then NUMA is enabled If the number of available nodes is ''1 nodes (0)'' then NUMA is not enabled. Voir aussi : * numastat * numademo #### NUMA (Non-Uniform Memory Access) - Useful Commands To identify NUMA nodes, socket memory and CPU core allocation ~~~bash numactl -H ~~~ To identify the NUMA node local to an adapter ~~~bash cat /sys/class/net//device/numa_node ~~~ To identify memory allocation and use on a particular NUMA node: ~~~bash cat /sys/devices/system/node/node/numastat ~~~ To identify NUMA node mapping to cores, use one of the following ~~~bash numactl --hardware cat /sys/devices/system/node/node/cpulist ~~~ Driver Loading - NUMA Node ~~~bash numactl --cpunodebind=1 onload_tool reload ~~~ ### Memory usage per user ~~~bash smem -u ~~~ ### Transparent HugePages (THP) Voir * https://blog.zwindler.fr/2020/02/24/transparent-hugepages-mesurer-limpact-sur-les-performances/ * https://www.postgresql.org/docs/9.4/kernel-resources.html #### Désactiver **Transparent HugePages (THP)** ~~~bash cat /sys/kernel/mm/transparent_hugepage/enabled ~~~ The following is a sample output that shows Transparent HugePages are being used as the [always] flag is enabled. ~~~ [always] never ~~~ Paramètre Kernel Linux ~~~ini transparent_hugepage=never ~~~ ## Notes Free / Aviable ~~~ $ ./centreon_plugins.pl --plugin os::linux::snmp::plugin --mode memory --hostname localhost --help ... --patch-redhat If using Red Hat distribution with net-snmp >= 5.7.2-43 and net-snmp < 5.7.2-47. But you should update net-snmp!!!! This version: used = memTotalReal - memAvailReal // free = memAvailReal Others versions: used = memTotalReal - memAvailReal - memBuffer - memCached // free = total - used ~~~ ## Exemple ~~~bash free -mt vmstat -SM 45 10 vmstat -SM -a 45 10 ps -C apache2 -o rss --no-headers |tr "\n" "+" | sed -e 's/+$/\n/' |bc ps -e -o pid,user,%mem,rss,vsize,cmd --sort rss ps -e -o pid,user,%mem,rss,vsize,cmd --sort vsize ps -u $USER -o comm,vsz,pcpu | sort -nrk2 ps -eo comm,pcpu,pmem,rss --sort rss | tail -n 30 | tac ~~~ ~~~bash read CommitLimit Committed_AS <<< $(egrep "CommitLimit|Committed_AS" /proc/meminfo |awk '{print $2}') echo $(( Committed_AS * 100 / CommitLimit)) ~~~ ~~~bash memused=$(free |grep "buffers/cache" |awk '{print $3}') memtotal=$(free |grep ^Mem | awk '{print $2}') echo $(( memused * 100 / memtotal)) ~~~ ~~~bash memFree=$(free |grep ^-|awk '{print $3}') memTot=$(free |grep ^Mem |awk '{print $2}') memUsed=$(echo "scale=2 ; 100 * $memFree / $memTot" |bc) echo "$memUsed % Mem used" | grep ^[3-9][0-9] ~~~ ~~~bash ps -C apache2 -o rss --no-headers |tr "\n" "+" | sed -e 's/+$/\n/' |bc read CommitLimit Committed_AS <<< $(egrep "CommitLimit|Committed_AS" /proc/meminfo |awk '{print $2}') echo $(( Committed_AS * 100 / CommitLimit)) memused=$(free |grep "buffers/cache" |awk '{print $3}') memtotal=$(free |grep ^Mem | awk '{print $2}') echo $(( memused * 100 / memtotal)) ps -e -o pid,user,rss,vsize,cmd --sort rss ~~~ ~~~bash smem -u smem -u -t -k top -b -n 1 -u apache ~~~ Taille totale de la mémoire physique de la RAM (sans la swap) ~~~ # head -1 /proc/meminfo MemTotal: 65391036 kB # awk '/MemTotal/ { print $2 }' /proc/meminfo 65391036 ~~~ ## Fonctionnement Voir : OOM Killer et Overcommit Memory http://www.blog.florian-bogey.fr/empecher-les-depassements-de-memoire-sur-un-serveur-linux.html ## Autres Clearing KernelCare Cache Source : https://www.linuxjournal.com/content/how-install-and-uninstall-kernelcare ~~~bash rm -rf /var/cache/kcare/patches echo 1 > /proc/sys/vm/compact_memory echo 3 > /proc/sys/vm/drop_caches kcarectl –update ~~~