From: Andi Kleen <andi@firstfloor.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <ak@linux.intel.com>, Andi Kleen <andi@firstfloor.org>,
linux-mm@kvack.org, Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@redhat.com>,
tim.c.chen@linux.intel.com, torvalds@linux-foundation.org,
lwoodman@redhat.com, mel@csn.ul.ie
Subject: Re: [PATCH 1/4] VM/RMAP: Add infrastructure for batching the rmap chain locking
Date: Tue, 10 May 2011 01:02:55 +0200 [thread overview]
Message-ID: <20110509230255.GA6008@one.firstfloor.org> (raw)
In-Reply-To: <20110509152841.ec957d23.akpm@linux-foundation.org>
On Mon, May 09, 2011 at 03:28:41PM -0700, Andrew Morton wrote:
> On Mon, 09 May 2011 15:23:03 -0700
> Andi Kleen <ak@linux.intel.com> wrote:
>
> > > After fixing that and doing an allnoconfig x86_64 build, the patchset
> > > takes rmap.o's .text from 6167 bytes to 6551. This is likely to be a
> > > regression for uniprocessor machines. What can we do about this?
> > >
> >
> > Regression in what way?
>
> It makes the code larger and probably slower, for no gain?
It should be actually faster because there are much less atomic ops.
Atomic ops are quite expensive -- especially on some older CPUs, even when
not contended.
>
> > I guess I can move some of the functions out of
> > line.
>
> I don't know how much that will help. Perhaps a wholesale refactoring
> and making it all SMP-only will be justified.
Yes I don't think there were a lot of callers.
I can take out the lockbreak. I was a bit dubious on its utility
anyways.
-Andi
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next prev parent reply other threads:[~2011-05-09 23:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-05 19:32 Batch locking for rmap fork/exit processing Andi Kleen
2011-05-05 19:32 ` [PATCH 1/4] VM/RMAP: Add infrastructure for batching the rmap chain locking Andi Kleen
2011-05-06 15:59 ` Rik van Riel
2011-05-09 21:43 ` Andrew Morton
2011-05-09 22:23 ` Andi Kleen
2011-05-09 22:28 ` Andrew Morton
2011-05-09 23:02 ` Andi Kleen [this message]
2011-05-09 23:16 ` Andrew Morton
2011-05-10 0:05 ` Andi Kleen
2011-05-10 1:26 ` Andrew Morton
2011-05-10 1:27 ` Rik van Riel
2011-05-10 1:48 ` Andrew Morton
2011-05-05 19:32 ` [PATCH 2/4] VM/RMAP: Batch anon vma chain root locking in fork Andi Kleen
2011-05-06 15:59 ` Rik van Riel
2011-05-05 19:32 ` [PATCH 3/4] VM/RMAP: Batch anon_vma_unlink in exit Andi Kleen
2011-05-06 16:48 ` Rik van Riel
2011-05-05 19:32 ` [PATCH 4/4] VM/RMAP: Move avc freeing outside the lock Andi Kleen
2011-05-06 16:52 ` Rik van Riel
2011-05-06 16:44 ` Batch locking for rmap fork/exit processing Linus Torvalds
2011-05-06 17:05 ` Andi Kleen
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