[CentOS] XFS and CentOS 4.3

Daniel de Kok danieldk at pobox.com
Wed Aug 16 21:44:53 UTC 2006


On Wed, 2006-08-16 at 16:08 -0500, Aleksandar Milivojevic wrote:
> Hmmm...  Any downside to setting it to 0?

Yeah. It disables the OOM killer, possibly leading to the situation
where no one can allocate memory. Having it enabled (and set to one
process) will try to pick a process according to the least surprise
principle.

> Node 0 Normal: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB  
> 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
> Node 0 HighMem: empty

Seems like a very bad OOM situation. Remember that the swapper is not
just an extension of physical memory, since kswapd has to take care of
paging out memory pages. If you are allocating huge chunks of memory in
a short time, you may want to crank up the vm.min_free_kbytes tunable.
This variable sets the low watermark of free memory, and setting it
higher gives the kernel more room for emergency allocations (e.g.
letting kswapd do its work). Setting it to 4096KB should help a lot,
though I have seen people setting it much higher on servers.

-- Daniel




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