From: Jeff Garzik <jgarzik@mandrakesoft.com>
To: "David S. Miller" <davem@redhat.com>
Cc: akpm@digeo.com, manfred@colorfullife.com, netdev@oss.sgi.com,
linux-kernel@vger.kernel.org
Subject: Re: Info: NAPI performance at "low" loads
Date: Tue, 17 Sep 2002 22:36:36 -0400 [thread overview]
Message-ID: <3D87E6B4.80304@mandrakesoft.com> (raw)
In-Reply-To: 20020917.190641.84134530.davem@redhat.com
David S. Miller wrote:
> From: Jeff Garzik <jgarzik@mandrakesoft.com>
> Date: Tue, 17 Sep 2002 22:11:14 -0400
>
> You're looking at at least one extra get-irq-status too, at least in the
> classical 10/100 drivers I'm used to seeing...
>
> How so? The number of ones done in the e1000 NAPI code are the same
> (read register until no interesting status bits remain set, same as
> pre-NAPI e1000 driver).
>
> For tg3 it's a cheap memory read from the status block not a PIO.
Non-NAPI:
get-irq-stat
ack-irq
get-irq-stat (omit, if no work loop)
NAPI:
get-irq-stat
ack-all-but-rx-irq
mask-rx-irqs
get-irq-stat (omit, if work loop)
...
ack-rx-irqs
get-irq-stat
unmask-rx-irqs
This is the low load / low latency case only. The number of IOs
decreases at higher loads [obviously :)]
next prev parent reply other threads:[~2002-09-18 2:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-17 19:53 Info: NAPI performance at "low" loads Manfred Spraul
2002-09-17 20:59 ` David S. Miller
2002-09-17 21:32 ` Andrew Morton
2002-09-17 21:26 ` David S. Miller
2002-09-17 21:45 ` Andrew Morton
2002-09-17 21:39 ` David S. Miller
2002-09-17 21:54 ` Jeff Garzik
2002-09-17 21:49 ` David S. Miller
2002-09-18 2:11 ` Jeff Garzik
2002-09-18 2:06 ` David S. Miller
2002-09-18 2:36 ` Jeff Garzik [this message]
2002-09-17 21:58 ` Andrew Morton
2002-09-18 0:57 ` jamal
2002-09-18 1:00 ` David S. Miller
2002-09-18 2:16 ` Andrew Morton
2002-09-18 17:27 ` Eric W. Biederman
2002-09-18 17:50 ` Alan Cox
2002-09-19 14:58 ` Eric W. Biederman
2002-09-18 20:23 ` David S. Miller
2002-09-18 20:43 ` Alan Cox
2002-09-18 20:46 ` David S. Miller
2002-09-18 21:15 ` Alan Cox
2002-09-18 21:22 ` David S. Miller
2002-09-19 15:03 ` Eric W. Biederman
2002-09-19 15:53 ` Alan Cox
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