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From: jamal <hadi@cyberus.ca>
To: Changli Gao <xiaosuo@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	netdev@vger.kernel.org
Subject: Re: [PATCH v3] net: batch skb dequeueing from softnet input_pkt_queue
Date: Wed, 14 Apr 2010 08:28:21 -0400	[thread overview]
Message-ID: <1271248101.3943.67.camel@bigi> (raw)
In-Reply-To: <o2k412e6f7f1004140513h8de62790tb775bb357e2db6b1@mail.gmail.com>

On Wed, 2010-04-14 at 20:13 +0800, Changli Gao wrote:
> On Wed, Apr 14, 2010 at 7:58 PM, jamal <hadi@cyberus.ca> wrote:

> No extra IPI is needed.
> 
> +       qlen = queue->input_pkt_queue.qlen + queue->processing_queue.qlen;
> +       if (qlen <= netdev_max_backlog) {
> +               if (qlen) {
> 
> the packets in processing_queue are counted too.

Ok - Looks reasonable.

> > IPIs add to latency (refer to my other email). Did you test this
> > to reach some conclusion that it improves thing or was it just by
> > inspection?
> >
> 
> :( only insepection.

I am probably being pushy, but one simple test for latency of single
flow is: 

from machine 1, send ping -f

on rps machine:
Base test: no rps on ( a fresh boot with no sysctls should do fine)
Test 1: irq affinity on cpuX, rps to cpuY 
Test 2: repeat test1 with your change.

It should show no difference between test1 and 2. If it shows
improvement better - but showing worse latency is bad.

cheers,
jamal


  reply	other threads:[~2010-04-14 12:28 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-14  9:52 [PATCH v3] net: batch skb dequeueing from softnet input_pkt_queue Changli Gao
2010-04-14 11:58 ` jamal
2010-04-14 12:13   ` Changli Gao
2010-04-14 12:28     ` jamal [this message]
2010-04-14 15:20 ` Eric Dumazet
2010-04-14 23:13   ` Changli Gao
2010-04-21 23:05 ` Eric Dumazet
2010-04-21 23:23   ` Tom Herbert
2010-04-22  1:35     ` Changli Gao
2010-04-22  6:33   ` Changli Gao
2010-04-22  7:13     ` Eric Dumazet
2010-04-22  7:17       ` David Miller
2010-04-22 12:13   ` jamal

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