From: Jesper Dangaard Brouer <brouer@redhat•com>
To: Jesper Dangaard Brouer <brouer@redhat•com>
Cc: Alexander Duyck <alexander.h.duyck@intel•com>,
David Miller <davem@davemloft•net>,
netdev@vger•kernel.org, therbert@google•com, jhs@mojatatu•com,
hannes@stressinduktion•org, edumazet@google•com,
jeffrey.t.kirsher@intel•com, rusty@rustcorp•com.au,
dborkman@redhat•com, Jeremy Eder <jeder@redhat•com>
Subject: Re: [PATCH 0/2] Get rid of ndo_xmit_flush
Date: Wed, 27 Aug 2014 10:37:29 +0200 [thread overview]
Message-ID: <20140827103729.69551e29@redhat.com> (raw)
In-Reply-To: <20140827094859.65f4f0fc@redhat.com>
On Wed, 27 Aug 2014 09:48:59 +0200
Jesper Dangaard Brouer <brouer@redhat•com> wrote:
> Reading Jeremy Eder's blog post:
> http://www.breakage.org/2012/11/14/processor-max_cstate-intel_idle-max_cstate-and-devcpu_dma_latency/
>
> It seems the best method for disabling these C and P states, and
> keeping all CPUs in C0/C1 state is doing:
>
> # tuned-adm profile latency-performance
[...]
> I'm also going to disable Hyper-threading in BIOS, even-though I'm only
> using one CPU in these tests (I worry that some process running on a
> sibling could disturb the accuracy).
Disabling Hyper-Threading in BIOS helped the accuracy, now the latency
variation is below 0.1ns min:-0.031 and max:0.054 over 120 sec.
Still using:
# tuned-adm profile latency-performance
> Setting:
> * sudo ethtool -C eth5 rx-usecs 30
> Result:
> * instant rx:1 tx:5603644 pps n:120 average: rx:0 tx:5603317 pps
> (instant variation TX 0.010 ns (min:-0.132 max:0.114) RX 0.000 ns)
> * instant rx:1 tx:5599820 pps n:300 average: rx:1 tx:5602382 pps
> (instant variation TX -0.082 ns (min:-0.209 max:0.114) RX 0.000 ns)
With no HT:
* instant rx:1 tx:5597616 pps n:120 average: rx:1 tx:5596283 pps
(instant variation TX 0.043 ns (min:-0.031 max:0.054) RX 0.000 ns)
With this setup, I think we are ready to measure the effect of our API
changes with sufficient accuracy.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Sr. Network Kernel Developer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2014-08-27 8:37 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-25 23:34 [PATCH 0/2] Get rid of ndo_xmit_flush David Miller
2014-08-26 6:28 ` Jesper Dangaard Brouer
2014-08-26 10:13 ` Jesper Dangaard Brouer
2014-08-26 12:52 ` Jesper Dangaard Brouer
2014-08-26 16:43 ` Alexander Duyck
2014-08-27 7:48 ` Jesper Dangaard Brouer
2014-08-27 8:37 ` Jesper Dangaard Brouer [this message]
2014-08-26 14:40 ` Jamal Hadi Salim
2014-09-01 0:37 ` Rusty Russell
2014-08-27 12:19 ` Jesper Dangaard Brouer
2014-08-27 20:43 ` David Miller
2014-08-27 12:31 ` Hannes Frederic Sowa
2014-08-27 13:23 ` Eric Dumazet
2014-08-27 13:56 ` Jesper Dangaard Brouer
2014-08-27 14:09 ` Eric Dumazet
2014-08-27 20:48 ` David Miller
2014-08-27 20:46 ` David Miller
2014-08-27 20:45 ` David Miller
2014-08-28 1:42 ` Hannes Frederic Sowa
2014-08-30 3:22 ` David Miller
2014-08-30 10:23 ` Jesper Dangaard Brouer
2014-09-01 20:05 ` Hannes Frederic Sowa
2014-09-01 21:56 ` David Miller
2014-09-01 22:31 ` Hannes Frederic Sowa
2014-09-01 22:35 ` David Miller
2014-08-27 18:28 ` Cong Wang
2014-08-27 19:31 ` Tom Herbert
2014-08-27 20:53 ` David Miller
2014-08-27 20:51 ` David Miller
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