linux-kernel - Re: [patch v2 0/4] percpu

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Date:	Thu, 14 Apr 2011 09:04:13 +0800
From:	Shaohua Li <shaohua.li@...el.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"tj@...nel.org" <tj@...nel.org>,
	"eric.dumazet@...il.com" <eric.dumazet@...il.com>
Subject: Re: [patch v2 0/4] percpu_counter: cleanup and fix

On Wed, 2011-04-13 at 22:08 +0800, Christoph Lameter wrote:
> On Wed, 13 Apr 2011, shaohua.li@...el.com wrote:
> 
> > Cleanup percpu_counter code and fix some bugs. The main purpose is to convert
> > percpu_counter to use atomic64, which is useful for workloads which cause
> > percpu_counter->lock contented. In a workload I tested, the atomic method is
> > 50x faster (please see patch 4 for detail).
> 
> Could you post your test and the results please?
the test is very simple, 24 processes in 24 CPU, and each does:
while (1) {
	mmap(128M);
	munmap(128M)
}
we then measure how many loops the process can do.
I'll attach the test in next post.
Just found when I said 50x faster, I actually forgot one other patch's
effect, which is http://marc.info/?l=linux-kernel&m=130127782901127&w=2.
If only having the atomic change, it's about 7x faster. Sorry about
this. I'll add detail data in next post.

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