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SubjectRe: [PATCH 0/8] sdhci: Move real work out of an atomic context
On Wed, Sep 08, 2010 at 11:05:48PM +0100, Chris Ball wrote:
> Hi Anton,
>
> On Thu, Sep 09, 2010 at 01:57:50AM +0400, Anton Vorontsov wrote:
> > Thanks!
> >
> > Would be also great if you could point out which patch causes
> > most of the performance drop (if any)?
> >
> > Albert, if you could find time, can you also "bisect" the
> > patchset? I wouldn't want to buy Nintendo WII just to debug the
> > perf regression. ;-) FWIW, I tried to disable multiblock
> > read/writes and test with SD cards, and still didn't notice
> > any performance drops.
> >
> > Maybe it's SDIO IRQs that cause the performance drop for the
> > WII case, as we delay them a little bit? Or it could be the
> > patch that introduces threaded IRQ handler in whole causes
> > it. If so, I guess we'd need to move some of the processing to
> > the real IRQ context, keeping the handler lockless (if
> > possible) or introducing a very fine grained locking.
>
> I didn't know anything about a reported performance drop, and I don't
> think Andrew did either -- Albert's test results don't seem to have
> made it to this list, or anywhere else that I can see. Could you
> link to/repost his comments?
>
> (I'll be testing with libertas, so that will stress-test SDIO IRQs.)

Sure thing, here are Albert's results.

----- Forwarded message from Albert Herranz <albert_herranz@yahoo.es> -----
Date: Mon, 02 Aug 2010 21:23:51 +0200
From: Albert Herranz <albert_herranz@yahoo.es>
To: Anton Vorontsov <cbouatmailru@gmail.com>
CC: akpm@linux-foundation.org, mm-commits@vger.kernel.org,
ben-linux@fluff.org, matt@console-pimps.org, pierre@ossman.eu,
w.sang@pengutronix.de, mb@bu3sch.de
Subject: Re: + sdhci-use-work-structs-instead-of-tasklets.patch added to -mm
tree

Hi,

Some initial numbers regarding performance. The patchset seems to cause a noticeable performance drop.
I've run two iperf client tests (see the two invocations of iperf -c) and two iperf server tests (see iperf -s invocation).

== 2.6.33 ==

$ iperf -c 192.168.1.130
------------------------------------------------------------
Client connecting to 192.168.1.130, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.127 port 40119 connected with 192.168.1.130 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.1 sec 1.05 MBytes 872 Kbits/sec
$ iperf -c 192.168.1.130
------------------------------------------------------------
Client connecting to 192.168.1.130, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.127 port 40120 connected with 192.168.1.130 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 1.04 MBytes 870 Kbits/sec
$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.127 port 5001 connected with 192.168.1.130 port 36691
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.2 sec 3.61 MBytes 2.98 Mbits/sec
[ 5] local 192.168.1.127 port 5001 connected with 192.168.1.130 port 36692
[ 5] 0.0-10.1 sec 4.94 MBytes 4.09 Mbits/sec

== 2.6.33 + "sdhci: Move real work out of an atomic context" patchset ==

$ iperf -c 192.168.1.130
------------------------------------------------------------
Client connecting to 192.168.1.130, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.127 port 39210 connected with 192.168.1.130 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 368 KBytes 301 Kbits/sec
$ iperf -c 192.168.1.130
------------------------------------------------------------
Client connecting to 192.168.1.130, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.127 port 39211 connected with 192.168.1.130 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.2 sec 440 KBytes 354 Kbits/sec
$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.127 port 5001 connected with 192.168.1.130 port 57833
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.2 sec 2.37 MBytes 1.95 Mbits/sec
[ 5] local 192.168.1.127 port 5001 connected with 192.168.1.130 port 57834
[ 5] 0.0-10.2 sec 2.30 MBytes 1.90 Mbits/sec
The subjective feeling is too that the system is slower.

Cheers,
Albert

----- End forwarded message -----

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