linux-kernel - Re: High latency on /sys/class/thermal

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Message-Id: <1239587022.7661.202.camel@rzhang-dt>
Date:	Mon, 13 Apr 2009 09:43:42 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	Tiago Simões Batista <tiagosbatista@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: High latency on /sys/class/thermal

this sounds like an EC problem to me. please attach the acpidump output.
is there a long latency when you poke other ACPI devices, say battery?

thanks,
rui

On Mon, 2009-04-13 at 00:03 +0800, Tiago Simões Batista wrote:
> On Sat, 11 Apr 2009 23:16:11 +0100
> Tiago Simões Batista <tiagosbatista@...il.com> wrote:
> 
> > Sorry about the noise, by brain was stopped when I sent the last mail,
> > please ignore the From address, it is wrong!
> > 
> > On Sat, 11 Apr 2009 12:14:16 -0700
> > Andrew Morton <akpm@...ux-foundation.org> wrote:
> > 
> > > (cc linux-acpi)
> > > 
> > > On Sat, 11 Apr 2009 15:56:12 +0100 "Tiago Sim__es Batista"
> > > <tiagosbatista@...il.com> wrote:
> > > 
> > > > Hi all
> > > > 
> > > > Yesterday, I recompiled my kernel (git + tuxonice)
> > > > v2.6.30-rc1-1002-gac91f91, there were a couple of issues, the main
> > > > one is ilustrated bellow.
> > > > 
> > > > I am not familiar with the kernel code, but if you give me some
> > > > pointers, I will be glad to investigate this further
> > > > 
> > > > $time cat /sys/class/thermal/thermal_zone0/temp 
> > > > 34000
> > > > 
> > > > real	0m6.613s
> > > > user	0m0.000s
> > > > sys	0m0.001s
> > > > 
> > > 
> > > Is this a regression?  Was 2.6.29 OK?
> > > 
> > > Thanks.
> > 
> > My last kernel was fine:
> > 
> > $ time cat /sys/class/thermal/thermal_zone0/temp 
> > 48000
> > 
> > real	0m0.007s
> > user	0m0.001s
> > sys	0m0.007s
> > 
> > 
> > I also forgot to add some information about my kernels...
> > 
> > The good one is 2.6.29 + tuxonice as it was the day after the 2.6.29
> > kernel was released.
> > 
> > The bad one is a pull from linus tree on april the 9th plus tuxonice
> > on the same day
> > 
> > from git (hope this helps):
> > $ git describe v2.6.29-tiago2-ice
> > v2.6.29-836-g00492ed
> > $ git describe v2.6.30-rc1-tiago1-ice
> > v2.6.30-rc1-1002-gac91f91
> > 
> > 
> > If tuxonice is a suspect, I will be glad to remove it and recompile.
> > If I have the time later this weekend, and nothing was found, I will
> > try to bisect this.
> > 
> 
> Here are some results from the bisect:
> The metric I used to mark a revision as good/bad was
> $ time for ((i =0; i < 100; i++)); do
>       cat /sys/class/thermal/thermal_zone0/temp > /dev/null; 
>   done
> 
> The bad ones take forever, i never even finished one bad run. The good
> ones take about half a second.
> 
> When I checked out revisions v2.6.29-148-g33526a5 and
> v2.6.29-159-g8a3f257, it took almost 2 secons to run the command, so I
> think some of the latency my have been introduced around these. Yet, I
> still marked them as good.
> 
> The resut was:
> 478c6a43fcbc6c11609f8cee7c7b57223907754f is first bad commit
> witch is a merge. I am out of ideas...
> 
> I forgot to ask, am I the only one experiencing this? I am using a
> TravelMate 4000 with the intel graphics chip, can anyone reproduce this?
> If no one can reproduce this, I can still test a vanilla kernel to
> remove TOI from the equation!
> 
> Tiago
> 
> 
> Below is the bisect log:
> $ git bisect log
> git bisect start
> # bad: [ac91f917d7ed7d1ebe14532ee137fcd759b4406d] Merge branch 'all' into all-tuxonice
> git bisect bad ac91f917d7ed7d1ebe14532ee137fcd759b4406d
> # good: [178a426510a901d9335f39d3391ae5e8628a36d1] Merge branch 'tuxonice' into all-tuxonice
> git bisect good 178a426510a901d9335f39d3391ae5e8628a36d1
> # good: [fdf9c9979a355916433262ea5e5e64bed5def86e] V4L/DVB (10465): dsbr100: Add few lost mutex locks.
> git bisect good fdf9c9979a355916433262ea5e5e64bed5def86e
> # good: [edbd606c4671fcd439164c8d63e896044d706156] Staging: wlan-ng: Replace WLAN_LOG_ERROR() with printk()
> git bisect good edbd606c4671fcd439164c8d63e896044d706156
> # good: [3516c6a8dc0b1153c611c4cf0dc4a51631f052bb] Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6
> git bisect good 3516c6a8dc0b1153c611c4cf0dc4a51631f052bb
> # bad: [3989203290fba6fdf6bc4825fbf6526e1bf17977] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
> git bisect bad 3989203290fba6fdf6bc4825fbf6526e1bf17977
> # bad: [d7ca6f8cdffa5765e486edb3dada9121fba8e6aa] Merge branch 'for-linus' of git://git.o-hand.com/linux-rpurdie-backlight
> git bisect bad d7ca6f8cdffa5765e486edb3dada9121fba8e6aa
> # good: [3b4dadf05d177289c279c50030c7c75e004952bb] Merge branch 'acpi_enforce_resources' into release
> git bisect good 3b4dadf05d177289c279c50030c7c75e004952bb
> # bad: [32fb6c17566ec66de87324a834c7776f40e35e78] Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
> git bisect bad 32fb6c17566ec66de87324a834c7776f40e35e78
> # good: [45e36c1666aa6c8b0c538abcf984b336184d8c3f] Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6
> git bisect good 45e36c1666aa6c8b0c538abcf984b336184d8c3f
> # good: [33526a53600ac887d100e3c9b4be3637ac8ae3a5] Merge branch 'x2apic' into release
> git bisect good 33526a53600ac887d100e3c9b4be3637ac8ae3a5
> # good: [c542aadeb4700bc316834d862d52ba3d2664f13a] panasonic-laptop: Fix autoloading
> git bisect good c542aadeb4700bc316834d862d52ba3d2664f13a
> # bad: [478c6a43fcbc6c11609f8cee7c7b57223907754f] Merge branch 'linus' into release
> git bisect bad 478c6a43fcbc6c11609f8cee7c7b57223907754f
> # good: [15065531c1c5902775ae3ade24eb37d0e688353b] toshiba-acpi: remove MAINTAINERS entry
> git bisect good 15065531c1c5902775ae3ade24eb37d0e688353b
> # good: [8a3f257c704e02aee9869decd069a806b45be3f1] Merge branch 'misc' into release
> git bisect good 8a3f257c704e02aee9869decd069a806b45be3f1

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