mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: starlight@binnacle.cx
To: linux-kernel@vger.kernel.org, netdev <netdev@vger.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Christoph Lameter <cl@gentwo.org>,
	Eric Dumazet <eric.dumazet@gmail.com>, Willy Tarreau <w@1wt.eu>,
	Ingo Molnar <mingo@elte.hu>,
	Stephen Hemminger <stephen.hemminger@vyatta.com>,
	Benjamin LaHaise <bcrl@kvack.org>, Joe Perches <joe@perches.com>,
	Chetan Loke <Chetan.Loke@netscout.com>,
	Con Kolivas <conman@kolivas.org>,
	Serge Belyshev <belyshev@depni.sinp.msu.ru>
Subject: Re: big picture UDP/IP performance question re 2.6.18  -> 2.6.32
Date: Thu, 06 Oct 2011 23:27:35 -0400	[thread overview]
Message-ID: <6.2.5.6.2.20111006231958.039bb570@binnacle.cx> (raw)

After writing the last post, the large
difference in IRQ rate between the older
and newer kernels caught my eye.

I wonder if the hugely lower rate in the older
kernels reflects a more agile shifting
into and out of NAPI mode by the network
bottom-half.

In this test the sending system
pulses data out on millisecond boundaries
due to the behavior of nsleep(), which
is used to establish the playback pace.

If the older kernels are switching to NAPI
for much of surge and the switching out
once the pulse falls off, it might
conceivably result in much better latency
and overall performance.

All tests were run with Intel 82571 
network interfaces and the 'e1000e'
device driver.  Some used the driver
packaged with the kernel, some used
Intel driver compiled from the source
found on sourceforge.net.  Never could
detected any difference between the two.

Since data in the production environment
also tends to arrive in bursts, I don't find
the pulsing playback behavior a detriment.


             reply	other threads:[~2011-10-07  3:33 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-07  3:27 starlight [this message]
2011-10-07  5:40 ` Eric Dumazet
2011-10-07  6:13   ` starlight
2011-10-07 18:09     ` chetan loke
     [not found]       ` <CAAsGZS4s1wTWW1j7FRUWW9jqpPUVF3Q46AMa7+njvE1ckX0Snw @mail.gmail.com>
2011-10-07 18:37         ` starlight
2011-10-07 19:27           ` chetan loke
     [not found]             ` <CAAsGZS4b2F9N3nV3TNu5xG+=2d0L0ncste4xv2vqoVFb1pOxEw @mail.gmail.com>
2011-10-07 19:41               ` starlight
2011-10-07 20:07           ` Ben Hutchings
2011-10-11 16:24   ` Chris Friesen
  -- strict thread matches above, loose matches on Subject: below --
2011-10-07  2:33 starlight
2011-10-07  2:24 starlight
2011-10-05  6:58 starlight
2011-10-05  8:53 ` Eric Dumazet
     [not found]   ` <1317804832.2473.25.camel@edumazet-HP-Compaq-6005-Pr o-SFF-PC>
2011-10-05 11:50     ` starlight
2011-10-05  6:11 starlight
2011-10-05  3:35 starlight
2011-10-03 18:02 starlight
2011-10-05  6:53 ` Eric Dumazet
2011-10-03 15:25 starlight
2011-10-03 16:16 ` Eric Dumazet
     [not found]   ` <1317658588.2442.5.camel@edumazet-HP-Compaq-6005-Pro -SFF-PC>
2011-10-03 16:28     ` starlight
2011-10-04 19:16 ` Christoph Lameter
2011-10-04 19:38   ` Joe Perches
2011-10-04 19:42     ` Christoph Lameter
2011-10-04 19:49       ` Serge Belyshev
2011-10-04 20:03         ` Christoph Lameter
2011-10-04 20:12           ` Serge Belyshev
2011-10-04 22:32             ` Con Kolivas
2011-10-04 19:45     ` starlight
2011-10-05 13:22   ` Peter Zijlstra
2011-10-05 14:26     ` Christoph Lameter
2011-10-05 15:12       ` Andi Kleen
2011-10-05 15:33       ` Peter Zijlstra
2011-10-05 15:12     ` starlight
2011-10-02  5:33 starlight
2011-10-02  7:21 ` Eric Dumazet
2011-10-02  8:03   ` Eric Dumazet
2011-10-02 14:47   ` Stephen Hemminger
2011-10-02 15:06   ` starlight
2011-10-04 19:54     ` Loke, Chetan
2011-10-01 21:13 starlight
2011-10-01 18:16 starlight
2011-10-01 18:40 ` Willy Tarreau
2011-10-01 19:11 ` Eric Dumazet
2011-10-01 19:43   ` starlight
2011-10-01  5:30 starlight
2011-10-01  6:44 ` Eric Dumazet
2011-10-01 15:56   ` starlight

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=6.2.5.6.2.20111006231958.039bb570@binnacle.cx \
    --to=starlight@binnacle.cx \
    --cc=Chetan.Loke@netscout.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=bcrl@kvack.org \
    --cc=belyshev@depni.sinp.msu.ru \
    --cc=cl@gentwo.org \
    --cc=conman@kolivas.org \
    --cc=eric.dumazet@gmail.com \
    --cc=joe@perches.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=netdev@vger.kernel.org \
    --cc=stephen.hemminger@vyatta.com \
    --cc=w@1wt.eu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®