Re: [PATCH] per-zone^Wnode kswapd process

From: Andrew Morton (akpm@digeo.com)
Date: Fri Sep 13 2002 - 20:19:36 EST


William Lee Irwin III wrote:
>
> ...
> On Fri, Sep 13, 2002 at 05:02:56PM -0700, Andrew Morton wrote:
> > Why do I see only one kswapd here?
> > Are you claiming an overall 4x improvement, or what?
> > I'll add some instrumentation whch tells us how many pages
> > kswapd is reclaiming versus direct reclaim.
>
> I can catch the others running if I refresh more often:
>
> 38 root 15 0 0 0 0 DW 4.8 0.0 1:57 kswapd0
> 36 root 15 0 0 0 0 SW 2.7 0.0 0:16 kswapd2
>
> 4779 wli 22 0 4476 3604 1648 R 9.2 0.0 0:58 top
> 37 root 15 0 0 0 0 SW 2.6 0.0 0:16 kswapd1
>
> 38 root 15 0 0 0 0 DW 2.9 0.0 2:12 kswapd0
> 36 root 15 0 0 0 0 SW 1.8 0.0 0:22 kswapd2
>
> 4779 wli 25 0 4476 3600 1648 R 7.4 0.0 1:18 top
> 37 root 15 0 0 0 0 SW 2.7 0.0 0:21 kswapd1
>
> 4779 wli 24 0 4476 3600 1648 R 37.5 0.0 1:49 top
> 37 root 16 0 0 0 0 RW 11.1 0.0 0:23 kswapd1
>
> 4779 wli 25 0 4476 3600 1648 R 14.1 0.0 1:51 top
> 35 root 15 0 0 0 0 SW 6.9 0.0 0:24 kswapd3
>
> 38 root 15 0 0 0 0 RW 2.9 0.0 2:29 kswapd0
> 37 root 16 0 0 0 0 SW 1.4 0.0 0:28 kswapd1
>
> etc.
>
> Not sure about baselines. I'm happier because there's more cpu
> utilization. kswapd0 is relatively busy so the other ones take some
> load off of it. The benchmark isn't quite done yet. I think four
> dbench 512's in parallel might be easier to extract results from.
> tiobench also looks like it's getting some cpu:
>

OK, thanks.

Could you please go into /proc/<pif_of_kswapd>/cpu and double
check that each kswapd is only racking up points on the CPUs
which it is supposed to be running on? As a little sanity check...

(hm. Why isn't cpus_allowed displayed from in there?)

Also, we need to double check that I'm not completely full of
unmentionables, and that kswapd really is doing useful work there.
I can check that.

I'll do an mm4 in a mo (as soon as I work out who did the dud patch
which stops it booting) and we can see what the kwapd-versus-direct-reclaim
ratio looks like.
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