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 22:11:14 -0400 [thread overview]
Message-ID: <3D87E0C2.6040004@mandrakesoft.com> (raw)
In-Reply-To: 20020917.144911.43656989.davem@redhat.com
David S. Miller wrote:
> From: Jeff Garzik <jgarzik@mandrakesoft.com>
> Date: Tue, 17 Sep 2002 17:54:42 -0400
>
> David S. Miller wrote:
> > Any driver should be able to get the NAPI overhead to max out at
> > 2 PIOs per packet.
>
> Just to pick nits... my example went from 2 or 3 IOs [depending on the
> presence/absence of a work loop] to 6 IOs.
>
> I mean "2 extra PIOs" not "2 total PIOs".
>
> I think it's doable for just about every driver, even tg3 with it's
> weird semaphore scheme takes 2 extra PIOs worst case with NAPI.
>
> The semaphore I have to ACK anyways at hw IRQ time anyways, and since
> I keep a software copy of the IRQ masking register, mask and unmask
> are each one PIO.
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...
Jeff
next prev parent reply other threads:[~2002-09-18 2:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3D879F59.6BDF9443@digeo.com>
[not found] ` <20020917.142635.114214508.davem@redhat.com>
2002-09-17 21:45 ` Info: NAPI performance at "low" loads 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 [this message]
2002-09-18 2:06 ` David S. Miller
2002-09-18 2:36 ` Jeff Garzik
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
2002-09-17 19:54 Manfred Spraul
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