From: Andi Kleen <ak@muc.de>
To: "David S. Miller" <davem@davemloft.net>
Cc: netdev@oss.sgi.com
Subject: Re: issue with new TCP TSO stuff
Date: 12 May 2005 22:26:29 +0200
Date: Thu, 12 May 2005 22:26:29 +0200 [thread overview]
Message-ID: <20050512202629.GB72662@muc.de> (raw)
In-Reply-To: <20050512.130341.82102354.davem@davemloft.net>
On Thu, May 12, 2005 at 01:03:41PM -0700, David S. Miller wrote:
> From: Andi Kleen <ak@muc.de>
> Subject: Re: issue with new TCP TSO stuff
> Date: 12 May 2005 22:02:51 +0200,Thu, 12 May 2005 22:02:51 +0200
>
> > Sure, but did you verify it was the actual problem? (e.g. with a profiler)
> > If the cache line the atomic operation is done on is EXCLUSIVE to the
> > CPU then it should not take *that* long to do the atomic operations.
>
> Such issues cannot be measured like that, they tend to make
> other operations slower by inducing cache misses elsewhere.
Atomic operations, especially with cache misses, normally show in a fine
grained profile. They also don't cause additional cache misses over
non atomic writes.
> I used my brain to analyze this slowdown, instead of the
> computer, I'm sorry if that disturbs you :-)
What disturbs me is your conclusion :)
-Andi
next prev parent reply other threads:[~2005-05-12 20:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-12 5:30 issue with new TCP TSO stuff David S. Miller
2005-05-12 10:05 ` Herbert Xu
2005-05-12 20:13 ` David S. Miller
2005-05-12 21:47 ` Herbert Xu
2005-05-12 22:10 ` Herbert Xu
2005-05-12 22:52 ` David S. Miller
2005-05-12 23:10 ` Herbert Xu
2005-05-12 23:24 ` David S. Miller
2005-05-12 23:52 ` Herbert Xu
2005-05-13 4:36 ` David S. Miller
2005-05-13 13:25 ` Herbert Xu
2005-05-12 22:46 ` David S. Miller
2005-05-12 14:13 ` Andi Kleen
2005-05-12 19:26 ` David S. Miller
[not found] ` <20050512200251.GA72662@muc.de>
2005-05-12 20:03 ` David S. Miller
2005-05-12 20:26 ` Andi Kleen [this message]
2005-05-12 22:34 ` David S. Miller
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