Difference between revisions of "Memory"

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(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]]
  
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Python, Linkers and Virtual Memory https://www.youtube.com/watch?v=twQKAoq2OPE
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Python, Likers 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
 
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 ==
 
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* 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>
 
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<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]]
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[[Category:Memory]]
 
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[[Category:Performance]]
 
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[[Category:Kernel]]
 
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[[Category:Configuration Management]]
 

Revision as of 00:36, 29 August 2014

Media-flash-memory-stick.svg

Python, Likers 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

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