Messages in this thread | | | Subject | Re: VM Problems in 2.6.7 (Too active OOM Killer) | From | Peter Zaitsev <> | Date | Wed, 14 Jul 2004 17:30:52 -0700 |
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On Wed, 2004-07-14 at 15:44, Andrew Morton wrote:
> > > To be honest I do not really understand this OOM without swap problem at > > all, why is it possible to move pages from ZONE_NORMAL to swap but not > > to other zones ? > > If the kernel has no swap there is nothing it can do with an anonymous page > (ie: the thing whcih malloc() gives you). It is effectively pinned memory, > because there's nowhere we can write it to get rid of it.
Why can't it be moved to other zone if there is a lot of place where ? In general I was not pushing system in some kind of stress mode - There was still a lot of cache memory available. Why it could not be instead shrunk to accommodate allocation ?
As I understand in my case with 4G there is Normal zone and HighMem zone where "user" anonymous memory can be located in any of these zones. Is this observation correct ?
> > If you end up pinning all of your ZONE_NORMAL pages with anonymous memory, > further GFP_KERNEL allocation attempts will go oom.
Aha I see. So user level memory allocations can't cause OOM only kernel level allocations can ? In this case why do not you have some reserved amount of space for these types of allocations by default ?
In this case I also do not understand how swap space helps here ? If you can't move page to over zone or shrink cache because of allocation type how it happens you can however perform page swap ?
-- Peter Zaitsev, Senior Support Engineer MySQL AB, www.mysql.com
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