From: Eric Dumazet <eric.dumazet@gmail.com>
To: Tom Herbert <therbert@google.com>
Cc: hadi@cyberus.ca, Changli Gao <xiaosuo@gmail.com>,
Rick Jones <rick.jones2@hp.com>,
David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, robert@herjulf.net, andi@firstfloor.org
Subject: Re: rps perfomance WAS(Re: rps: question
Date: Sat, 17 Apr 2010 11:23:49 +0200 [thread overview]
Message-ID: <1271496229.16881.4602.camel@edumazet-laptop> (raw)
In-Reply-To: <z2q65634d661004170143nb35ec784mbedd003565410cfb@mail.gmail.com>
Le samedi 17 avril 2010 à 01:43 -0700, Tom Herbert a écrit :
> > So the cost of queing the packet into our own queue (netif_receive_skb
> > -> enqueue_to_backlog) is about 0.74 us (74 ms / 100000)
> >
> > I personally think we should process packet instead of queeing it, but
> > Tom disagree with me.
> >
> You could do that, but then the packet processing becomes HOL blocking
> on all the packets that are being sent to other queues for
> processing-- remember the IPIs is only sent at the end of the NAPI.
> So unless the upper stack processing is <0.74us in your case, I think
> processing packets directly on the local queue would improve best case
> latency, but would increase average latency and even more likely worse
> case latency on loads with multiple flows.
Anyway, a big part of this 0.74 us overhead comes from get_rps_cpu()
itself, computing skb->rxhash and all. We should make a review of how
many cache lines we exchange per skb, and try to reduce this number.
next prev parent reply other threads:[~2010-04-17 9:23 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-07 18:42 rps: question jamal
2010-02-08 5:58 ` Tom Herbert
2010-02-08 15:09 ` jamal
2010-04-14 11:53 ` rps perfomance WAS(Re: " jamal
2010-04-14 17:31 ` Tom Herbert
2010-04-14 18:04 ` Eric Dumazet
2010-04-14 18:53 ` jamal
2010-04-14 19:44 ` Stephen Hemminger
2010-04-14 19:58 ` Eric Dumazet
2010-04-15 8:51 ` David Miller
2010-04-14 20:22 ` jamal
2010-04-14 20:27 ` Eric Dumazet
2010-04-14 20:38 ` jamal
2010-04-14 20:45 ` Tom Herbert
2010-04-14 20:57 ` Eric Dumazet
2010-04-14 22:51 ` Changli Gao
2010-04-14 23:02 ` Stephen Hemminger
2010-04-15 2:40 ` Eric Dumazet
2010-04-15 2:50 ` Changli Gao
2010-04-15 8:57 ` David Miller
2010-04-15 12:10 ` jamal
2010-04-15 12:32 ` Changli Gao
2010-04-15 12:50 ` jamal
2010-04-15 23:51 ` Changli Gao
2010-04-15 8:51 ` David Miller
2010-04-14 20:34 ` Andi Kleen
2010-04-15 8:50 ` David Miller
2010-04-15 8:48 ` David Miller
2010-04-15 11:55 ` jamal
2010-04-15 16:41 ` Rick Jones
2010-04-15 20:16 ` jamal
2010-04-15 20:25 ` Rick Jones
2010-04-15 23:56 ` Changli Gao
2010-04-16 5:18 ` Eric Dumazet
2010-04-16 6:02 ` Changli Gao
2010-04-16 6:28 ` Tom Herbert
2010-04-16 6:32 ` Eric Dumazet
2010-04-16 13:42 ` jamal
2010-04-16 7:15 ` Andi Kleen
2010-04-16 13:27 ` jamal
2010-04-16 13:37 ` Andi Kleen
2010-04-16 13:58 ` jamal
2010-04-16 13:21 ` jamal
2010-04-16 13:34 ` Changli Gao
2010-04-16 13:49 ` jamal
2010-04-16 14:10 ` Changli Gao
2010-04-16 14:43 ` jamal
2010-04-16 14:58 ` Changli Gao
2010-04-19 12:48 ` jamal
2010-04-17 7:35 ` Eric Dumazet
2010-04-17 8:43 ` Tom Herbert
2010-04-17 9:23 ` Eric Dumazet [this message]
2010-04-17 14:27 ` Eric Dumazet
2010-04-17 17:26 ` Tom Herbert
2010-04-17 14:17 ` [PATCH net-next-2.6] net: remove time limit in process_backlog() Eric Dumazet
2010-04-18 9:36 ` David Miller
2010-04-17 17:31 ` rps perfomance WAS(Re: rps: question jamal
2010-04-18 9:39 ` Eric Dumazet
2010-04-18 11:34 ` Eric Dumazet
2010-04-19 2:09 ` jamal
2010-04-19 9:37 ` [RFC] rps: shortcut net_rps_action() Eric Dumazet
2010-04-19 9:48 ` Changli Gao
2010-04-19 12:14 ` Eric Dumazet
2010-04-19 12:28 ` Changli Gao
2010-04-19 13:27 ` Eric Dumazet
2010-04-19 14:22 ` Eric Dumazet
2010-04-19 15:07 ` [PATCH net-next-2.6] " Eric Dumazet
2010-04-19 16:02 ` Tom Herbert
2010-04-19 20:21 ` David Miller
2010-04-20 7:17 ` [PATCH net-next-2.6] rps: cleanups Eric Dumazet
2010-04-20 8:18 ` David Miller
2010-04-19 23:56 ` [PATCH net-next-2.6] rps: shortcut net_rps_action() Changli Gao
2010-04-20 0:32 ` Changli Gao
2010-04-20 5:55 ` Eric Dumazet
2010-04-20 12:02 ` rps perfomance WAS(Re: rps: question jamal
2010-04-20 13:13 ` Eric Dumazet
[not found] ` <1271853570.4032.21.camel@bigi>
2010-04-21 19:01 ` Eric Dumazet
2010-04-22 1:27 ` Changli Gao
2010-04-22 12:12 ` jamal
2010-04-25 2:31 ` Changli Gao
2010-04-26 11:35 ` jamal
2010-04-26 13:35 ` Changli Gao
2010-04-21 21:53 ` Rick Jones
2010-04-16 15:57 ` Tom Herbert
2010-04-14 18:53 ` Stephen Hemminger
2010-04-15 8:42 ` David Miller
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