Re: [PATCH 17/18] fs: icache remove inode_lock

Nick Piggin
2010-10-13T12:07:12Z

On Wed, Oct 13, 2010 at 12:42:36PM +0200, Eric Dumazet wrote:
> Le mercredi 13 octobre 2010 à 18:20 +1100, Nick Piggin a écrit :
>
> > 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.
> >
>
> Hi Nick
>
> Not vastly urgent, but highly wanted on many workloads, even ones not
> really related to 'fs'...
>
> In current tree, a "close(socket())" needs 31 us on a 2x4x2 machine,
> instead of 1.45 us if single thread.
>
> 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