linux-kernel - Re: Very aggressive memory reclaim

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Date:	Tue, 29 Mar 2011 12:57:27 +1100
From:	Dave Chinner <david@...morbit.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	John Lepikhin <johnlepikhin@...il.com>,
	linux-kernel@...r.kernel.org, xfs@....sgi.com, linux-mm@...ck.org
Subject: Re: Very aggressive memory reclaim

On Mon, Mar 28, 2011 at 04:58:50PM -0700, Andi Kleen wrote:
> Dave Chinner <david@...morbit.com> writes:
> >
> > First it would be useful to determine why the VM is reclaiming so
> > much memory. If it is somewhat predictable when the excessive
> > reclaim is going to happen, it might be worth capturing an event
> 
> Often it's to get pages of a higher order. Just tracing alloc_pages
> should tell you that.

Yes, the kmem/mm_page_alloc tracepoint gives us that. But in case
that is not the cause, grabbing all the trace points I suggested is
more likely to indicate where the problem is. I'd prefer to get more
data than needed the first time around than have to do multiple
round trips because a single trace point doesn't tell us the cause...

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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