From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nick Piggin <npiggin@kernel.dk>
Subject: Re: [PATCH 17/18] fs: icache remove inode_lock
Date: Wed, 13 Oct 2010 23:07:06 +1100
Message-ID: <20101013120706.GB5883@amd>
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Cc: Nick Piggin <npiggin@kernel.dk>,
	Dave Chinner <david@fromorbit.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
To: Eric Dumazet <eric.dumazet@gmail.com>
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On Wed, Oct 13, 2010 at 12:42:36PM +0200, Eric Dumazet wrote:
> Le mercredi 13 octobre 2010 =E0 18:20 +1100, Nick Piggin a =E9crit :
>=20
> > I don't think the patchset has suddenly become vastly more urgent
> > in the past month, so I think my approach of having it get a lot
> > of testing and go in Al's vfs tree for a while is best.
> >=20
>=20
> Hi Nick=20
>=20
> Not vastly urgent, but highly wanted on many workloads, even ones not
> really related to 'fs'...
>=20
> In current tree, a "close(socket())" needs 31 us on a 2x4x2 machine,
> instead of 1.45 us if single thread.
>=20
> But yes, I agree a lot of testing is needed :)

Hi Eric,

Yes of course I know you know about this :) And google knows about it
too -- they of course posted the batched iput/dput patches a couple of
years back when they noticed it on their socket workloads. I've
extensively tested the socket paths during development of the patches,
and on a POWER7 system with many hundreds of threads, it scales
completely linearly!

I acknowledge that the vfs scale work is actually quite urgent, and
probably at least a year overdue (2.6.32 would have been nice target
for distros). I just mean that it hasn't suddenly gone from less to
much more important to push this in now before I review it or before
it has had a chance in vfs tree.

Thanks,
Nick