Difference between revisions of "Memory"
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(Created page with "File:Media-flash-memory-stick.svg Python, Likers and Virtual Memory https://www.youtube.com/watch?v=twQKAoq2OPE Category:System Administration") |
(Document some of the things I learned about Transparent HugePages) |
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| − | File:Media-flash-memory-stick.svg | + | [[File:Media-flash-memory-stick.svg]] |
| − | Python, | + | Python, Linkers and Virtual Memory https://www.youtube.com/watch?v=twQKAoq2OPE |
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| + | Reporting on "actual" memory usage of your application with smem http://linuxaria.com/pills/linux-terminal-check-who-uses-all-your-memory-with-smem | ||
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| + | ==Transparent Hugepages == | ||
| + | * https://access.redhat.com/solutions/46111 for Fedora and RHEL Note: their commands at the end of the article for determining if HugePages are disabled do not work in my limited tests. I have both Ubuntu and CentOS systems which are using HugePages, yet <code>grep -i HugePages_Total /proc/meminfo</code> <code>cat /proc/sys/vm/nr_hugepages</code> and <code>sysctl vm.nr_hugepages</code> all report zero. Meanwhile <code>grep AnonHugePages /proc/meminfo</code> and <code>grep -e AnonHugePages /proc/*/smaps | awk '{ if($2>4) print $0} ' | awk -F "/" '{print $0; system("ps -fp " $3)} '</code> report actual usage. The biggest applications? [[mysql]]d, [[java]], [[python]], [[node]], polkitd, [[mongo]]d, [[httpd]] | ||
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| + | Strangely, the value for <code>cat /sys/kernel/mm/transparent_hugepage/enabled</code> | ||
| + | <pre>[always] madvise never</pre> | ||
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| + | Note that in order to enable or disable THP ''permanently'' (so that it survives reboots), you need to do more than just echo a value to <code>/sys/kernel/mm/transparent_hugepage/enabled</code>. And there are subtle differences between distros. <ref>https://askubuntu.com/questions/597372/how-do-i-modify-sys-kernel-mm-transparent-hugepage-enabled</ref> | ||
[[Category:System Administration]] | [[Category:System Administration]] | ||
| + | [[Category:Memory]] | ||
| + | [[Category:Performance]] | ||
| + | [[Category:Kernel]] | ||
| + | [[Category:Configuration Management]] | ||
Latest revision as of 17:13, 26 July 2018
Python, Linkers and Virtual Memory https://www.youtube.com/watch?v=twQKAoq2OPE
Reporting on "actual" memory usage of your application with smem http://linuxaria.com/pills/linux-terminal-check-who-uses-all-your-memory-with-smem
Transparent Hugepages[edit | edit source]
- https://access.redhat.com/solutions/46111 for Fedora and RHEL Note: their commands at the end of the article for determining if HugePages are disabled do not work in my limited tests. I have both Ubuntu and CentOS systems which are using HugePages, yet
grep -i HugePages_Total /proc/meminfocat /proc/sys/vm/nr_hugepagesandsysctl vm.nr_hugepagesall report zero. Meanwhilegrep AnonHugePages /proc/meminfoandgrep -e AnonHugePages /proc/*/smaps | awk '{ if($2>4) print $0} ' | awk -F "/" '{print $0; system("ps -fp " $3)} 'report actual usage. The biggest applications? mysqld, java, python, node, polkitd, mongod, httpd
Strangely, the value for cat /sys/kernel/mm/transparent_hugepage/enabled
[always] madvise never
Note that in order to enable or disable THP permanently (so that it survives reboots), you need to do more than just echo a value to /sys/kernel/mm/transparent_hugepage/enabled. And there are subtle differences between distros. [1]
