From: Eric Lemoine <eric.lemoine@gmail.com>
To: Stephen Hemminger <shemminger@osdl.org>
Cc: hadi@znyx.com, "David S. Miller" <davem@davemloft.net>,
netdev <netdev@oss.sgi.com>
Subject: Re: [RFC] netif_rx: receive path optimization
Date: Thu, 31 Mar 2005 23:43:27 +0200 [thread overview]
Message-ID: <5cac192f05033113434742aeb4@mail.gmail.com> (raw)
In-Reply-To: <20050331131707.69f451ea@dxpl.pdx.osdl.net>
> > > Here is another alternative that seems better than the earlier posting. It uses
> > > a per device receive queue for non-NAPI devices. The only issue is that then
> > > we lose the per-cpu queue's and that could impact the loopback device performance.
> > > If that is really an issue, then the per-cpu magic should be moved to the loopback
> > > device.
> > >
> >
> > The repurcassions of going from per-CPU-for-all-devices queue
> > (introduced by softnet) to per-device-for-all-CPUs maybe huge in my
> > opinion especially in SMP. A closer view of whats there now maybe
> > per-device-per-CPU backlog queue.
>
> Any real hardware only has a single receive packet source (the interrupt routine),
> and the only collision would be in the case of interrupt migration. So having
> per-device-per-CPU queue's would be overkill and more complex because
> the NAPI scheduling is per-netdevice rather than per-queue (though that
> could be fixed).
>
> > I think performance will be impacted in all devices. imo, whatever needs
> > to go in needs to have some experimental data to back it
>
> Experiment with what? Proving an absolute negative is impossible.
> I will test loopback and non-NAPI version of a couple of gigabit drivers
> to see.
Just a naive question : why at all trying to accelerate netif_rx?
Isn't NAPI the best choice for high performance rx anyway?
--
Eric
next prev parent reply other threads:[~2005-03-31 21:43 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-30 21:28 [PATCH] netif_rx: receive path optimization Stephen Hemminger
2005-03-30 21:57 ` jamal
2005-03-30 22:08 ` jamal
2005-03-30 23:53 ` Stephen Hemminger
2005-03-31 3:16 ` jamal
2005-03-31 20:04 ` [RFC] " Stephen Hemminger
2005-03-31 21:10 ` Jamal Hadi Salim
2005-03-31 21:17 ` Stephen Hemminger
2005-03-31 21:25 ` Jamal Hadi Salim
2005-03-31 21:43 ` Eric Lemoine [this message]
2005-03-31 22:02 ` Stephen Hemminger
2005-03-31 21:24 ` Rick Jones
2005-03-31 21:38 ` jamal
2005-03-31 22:42 ` Rick Jones
2005-03-31 23:03 ` Nivedita Singhvi
2005-03-31 23:28 ` Rick Jones
2005-04-01 0:10 ` Stephen Hemminger
2005-04-01 0:42 ` Rick Jones
2005-04-01 0:30 ` Nivedita Singhvi
2005-03-31 23:36 ` jamal
2005-04-01 0:07 ` Rick Jones
2005-04-01 1:17 ` jamal
2005-04-01 18:22 ` Rick Jones
2005-04-01 16:40 ` Andi Kleen
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