From: Andi Kleen <ak@muc.de>
To: "David S. Miller" <davem@davemloft.net>
Cc: cndougla@purdue.edu, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org
Subject: Re: TCP prequeue performance
Date: Thu, 16 Jun 2005 02:23:59 +0200 [thread overview]
Message-ID: <m17jgv9mjk.fsf@muc.de> (raw)
In-Reply-To: <20050615.164115.74747690.davem@davemloft.net> (David S. Miller's message of "Wed, 15 Jun 2005 16:41:15 -0700 (PDT)")
"David S. Miller" <davem@davemloft.net> writes:
>
> Not true, if this check does not pass, tp->ucopy.task is
> never set, therefore prequeue processing is never performed.
Oh well, here goes my nice theory :)
>
> This test must pass the first time, when both tp->ucopy.task
> and user_recv are both NULL, in order for prequeue processing
> to occur at all.
>
> So his change did totally disable prequeue.
Then probably his test was latency bound somehow, but normally
that should not affect system time, just wall time.
I would perhaps compare context switch numbers and netstat -s
output between the different runs and see if anything pops out.
-Andi
prev parent reply other threads:[~2005-06-16 0:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-15 20:31 TCP prequeue performance Chase Douglas
2005-06-15 20:51 ` David S. Miller
2005-06-15 23:34 ` Andi Kleen
2005-06-15 23:41 ` David S. Miller
2005-06-16 0:23 ` Andi Kleen [this message]
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