From: Eric Dumazet <eric.dumazet@gmail.com>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: netdev@vger.kernel.org
Subject: Re: UDP regression with packets rates < 10k per sec
Date: Thu, 10 Sep 2009 23:37:07 +0200 [thread overview]
Message-ID: <4AA97183.3030008@gmail.com> (raw)
In-Reply-To: <4AA963A4.5080509@gmail.com>
Eric Dumazet a écrit :
> Something must be wrong with program or whatever...
>
> On the receiver I did this to trace the latency messages only
>
> # tcpdump -i eth0 not host 239.0.192.2 and port 9002 -n
>
> 22:28:07.223300 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
> 22:28:07.223403 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
>
> 22:28:08.223301 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
> 22:28:08.223416 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
>
> 22:28:09.223380 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
> 22:28:09.223494 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
>
> 22:28:10.223481 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
> 22:28:10.223597 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
>
> 22:28:11.223581 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
> 22:28:11.223678 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
>
>
> See how the answer is *very* slow ? Something like > 100 us ?
>
Never mind, this is OK, after proper irq affinity and tweaks on receiver :
(I should do same on other machine as well...)
(echo 1 >/proc/irq/default_smp_affinity) before up-ing bnx2 NIC
echo performance >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
and idle=mwait (or hpet and C2/C3 states are used on this machine and
wakeups are slow)
# tcpdump -i eth0 not host 239.0.192.2 and port 9002 -n
23:25:02.137143 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
23:25:02.137212 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
23:25:03.137204 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
23:25:03.137288 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
23:25:04.137276 IP 55.225.18.7.9002 > 55.225.18.5.9002: UDP, length 32
23:25:04.137355 IP 55.225.18.5.9002 > 55.225.18.7.9002: UDP, length 32
I presume powersaving improvements in last kernels are against
latencies goals...
next prev parent reply other threads:[~2009-09-10 21:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-08 22:38 UDP regression with packets rates < 10k per sec Christoph Lameter
2009-09-08 22:52 ` Eric Dumazet
2009-09-09 14:01 ` Christoph Lameter
2009-09-09 15:09 ` Eric Dumazet
2009-09-09 16:47 ` Christoph Lameter
2009-09-09 17:06 ` Eric Dumazet
2009-09-09 17:55 ` Christoph Lameter
2009-09-10 20:37 ` Eric Dumazet
2009-09-10 21:36 ` Christoph Lameter
2009-09-10 21:37 ` Eric Dumazet [this message]
2009-09-10 21:42 ` Christoph Lameter
2009-09-14 21:10 ` Christoph Lameter
2009-09-15 5:29 ` Eric Dumazet
2009-09-15 14:07 ` Christoph Lameter
2009-09-15 17:26 ` Eric Dumazet
2009-09-15 20:25 ` Christoph Lameter
2009-09-15 19:02 ` Eric Dumazet
2009-09-25 14:19 ` Eric Dumazet
2009-09-26 16:13 ` Christoph Lameter
2009-09-10 21:39 ` Christoph Lameter
2009-09-09 17:08 ` Eric Dumazet
2009-09-09 17:26 ` Christoph Lameter
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=4AA97183.3030008@gmail.com \
--to=eric.dumazet@gmail.com \
--cc=cl@linux-foundation.org \
--cc=netdev@vger.kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.