How do I determine the value of vm_page_free_target based on memory?

[watermelonyu]

根據 HP 文件 http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51_PDF/ARH9GBTE.PDF ,

Memory 大於 4096 MB 時, 則 vm_page_free_target 需設 1024, 但當 memory 達到 20GB 時, 是否該把值調得更大, 對於 performance 會有哪些影響?

[watermelonyu]

vm_page_free_target是個Paging threshold的值

我認為如果將的的值再加大,會導致其實你還有很多free page但是卻已經paging start

example 你的Memory is 4096

if free paes lower than 1024(8M)，paging start

所以你將這個值加大,會導致你的free page 其實還有剩餘,但是卻開始paging

[watermelonyu]

Hi,



Please see both "vm_page_free_target" and "vm_page_free_hardswap" via "# sysconfig -q vm".



The "vm_page_free_hardswap" was calculated by the "vm_page_free_target" setting.



The paging start the free_mem lower then "vm_page_free_hardswap".

The swaping start the free_mem lower than "vm_page_free_target".



Suggest to tune the vm_page_free_target to 2048 ~ 4096 for avoiding a large job running but it is slow to swap due to no free memory.



Best regards,

Richard.