Messages in this thread | | | Date | Wed, 10 Nov 2004 12:11:16 +1100 | From | Nick Piggin <> | Subject | Re: [PATCH] Remove OOM killer from try_to_free_pages / all_unreclaimable braindamage |
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Marcelo Tosatti wrote:
>On Mon, Nov 08, 2004 at 06:35:52PM -0800, Andrew Morton wrote: > >>Nick Piggin <piggin@cyberone.com.au> wrote: >> >>>I'm not sure... it could also be just be a fluke >>> due to chaotic effects in the mm, I suppose :| >>> >>2.6 scans less than 2.4 before declaring oom. I looked at the 2.4 >>implementation and thought "whoa, that's crazy - let's reduce it and see >>who complains". My three-year-old memory tells me it was reduced by 2x to >>3x. >> >>We need to find testcases (dammit) and do the analysis. It could be that >>we're simply not scanning far enough. >> > >Andrew, > >When reading the code I was really suspicious of the all_unreclaimable code. >It basically stops scanning when reaching OOM conditions - that might be it. > >
Yeah, I saw a pretty good correlation between OOM killing and all_unreclaimable.
We've got some code to spit that out during an OOM kill now, so that might be helpful.
>I tried to disable it (ignore it if priority==0) - result: very slow progress >on extreme load. > >
I had a patch that caused try_to_free_pages to ignore all_unreclaimable and go 'round the loop again if we reached oom-kill conditions. Basically that guarantees you'll scan ~ pages_present*2 before going OOM. I think it may be a good thing to do, but I wasn't really able to reproduce these early OOM killings.
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