Messages in this thread | | | Date | Wed, 15 Jul 2009 20:51:09 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH -mm] throttle direct reclaim when too many pages are isolated already |
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On Wed, 15 Jul 2009 23:42:28 -0400 Rik van Riel <riel@redhat.com> wrote:
> Andrew Morton wrote: > > On Wed, 15 Jul 2009 23:28:14 -0400 Rik van Riel <riel@redhat.com> wrote: > > >> If we are stuck at this point in the page reclaim code, > >> it is because too many other tasks are reclaiming pages. > >> > >> That makes it fairly safe to just return SWAP_CLUSTER_MAX > >> here and hope that __alloc_pages() can get a page. > >> > >> After all, if __alloc_pages() thinks it made progress, > >> but still cannot make the allocation, it will call the > >> pageout code again. > > > > Which will immediately return because the caller still has > > fatal_signal_pending()? > > Other processes are in the middle of freeing pages at > this point, so we should succeed in __alloc_pages() > fairly quickly (and then die and free all our memory).
What if it's a uniprocessor machine and all those processes are scheduled out? We sit there chewing 100% CPU and not doing anything afaict.
Even if it _is_ SMP, we could still chew decent-sized blips of CPU time rattling around waiting for something to happen.
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