Re: [PATCH v6 12/31] fs: convert inode and dentry shrinking to be node aware

Dave Chinner
2013-05-18T03:39:41Z

On Fri, May 17, 2013 at 06:49:37PM +0400, Glauber Costa wrote:
> On 05/17/2013 11:29 AM, Glauber Costa wrote:
> > Except that shrink_slab_node would also defer work, right?
> >
> >> > The only thing I don't like about this is the extra nodemask needed,
> >> > which, like the scan control, would have to sit on the stack.
> >> > Suggestions for avoiding that problem are welcome.. :)
> >> >
> > I will try to come up with a patch to do all this, and then we can
> > concretely discuss.
> > You are also of course welcome to do so as well =)
>
>
> All right.
>
> I played a bit today with variations of this patch that will keep the
> deferred count per node. I will rebase the whole series ontop of it (the
> changes can get quite disruptive) and post. I want to believe that
> after this, all our regression problems will be gone (famous last words).
>
> As I have told you, I wasn't seeing problems like you are, and
> speculated that this was due to the disk speeds. While this is true,
> the patch I came up with makes my workload actually a lot better.
> While my caches weren't being emptied, they were being slightly depleted
> and then slowly filled again. With my new patch, it is almost
> a straight line throughout the whole find run. There is a dent here and
> there eventually, but it recovers quickly. It takes some time as well
> for steady state to be reached, but once it is, we have all variables
> in the equation (dentries, inodes, etc) basically flat. So I guess it
> works, and I am confident that it will make your workload better.

Sounds promising. A non-numa system gives dead flat linesonthat
workload, and that's how I want a numa system to behave as well when
there is even pressure applied across all nodes.

Sorry for not doing more here - I've been flat out the last couple
of days with XFS CRC stuff. Let me know when you have a tree rebased
as far as this patch and I'll run some tests here....

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com

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