Re: Memory usage per memory zone

[Wu Fengguang <fengguang.wu@intel.com>]

On Wed, Mar 11, 2009 at 01:51:32PM +0200, jack marrow wrote:
> 2009/3/11 Wu Fengguang <fengguang.wu@intel.com>:
> > Hi jack,
> >
> > On Wed, Mar 11, 2009 at 11:41:43AM +0100, jack marrow wrote:
> >> Hello,
> >>
> >> I have a box where the oom-killer is killing processes due to running
> >> out of memory in zone_normal. I can see using slabtop that the inode
> >
> > How do you know that the memory pressure on zone normal stand out alone?
> 
> For the normal zone only, I see "all_unreclaimable: yes" and 3 megs of free ram:
> 
> kernel: Normal free:2576kB min:3728kB low:7456kB high:11184kB
> active:1304kB inactive:128kB present:901120kB pages_scanned:168951
> all_unreclaimable? yes

It's normal behavior.  Linux kernel tries hard to utilize most of
the free memory for caching files :)

> >> caches are using up lots of memory and guess this is the problem, so
> >> have cleared them using an echo to drop_caches.
> >
> > It would better be backed by concrete numbers...
> >
> >>
> >> I would quite like to not guess though - is it possible to use slabtop
> >> (or any other way) to view ram usage per zone so I can pick out the
> >> culprit?
> >
> > /proc/zoneinfo and /proc/vmstat do have some per-zone numbers.
> > Some of them deal with slabs.
> 
> Thanks, I'll read up on how to interpret these.
> 
> Do you recommend these two files for tracking down memory usage per
> process per zone?

No, the two interfaces provide system wide counters.  We have the well
known tools "ps" and "top" for per-process numbers, hehe.

Thanks,
Fengguang

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