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SubjectRe: v2.6.21.5-rt19
Fernando Lopez-Lezcano wrote:
> On Sat, 2007-07-07 at 11:24 +0200, Ingo Molnar wrote:
>
>> * Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU> wrote:
>>
>>>>> Changes since 2.6.21.5-rt18:
>>>>>
>>>>> - Fixed a nasty and hard to track down slowness / boot problem on SMP
>>>>> machines with CONFIG_NOHZ enabled. The problem was caused by the timer
>>>>> wheel base lock held during the get_next_timer_interrupt() call in the
>>>>> idle path, which eventually led to a bogus PI boosting of the idle task
>>>>> and in consequence a stale wrong scheduler selection for the affected idle
>>>>> task.
>>>>>
>>>>> Kudos to Carsten Emde, who patiently and meticulously isolated the
>>>>> problem and provided the traces, which allowed to identify the root cause.
>>>>>
>>>>> Problem solution: Prevent idle task boosting
>>>>>
>>>> Maybe someone remember me whining about troubles with 2.6.21-rt2..18
>>>> on my Core2 T7200 laptop (fujitsu-siemens amilo i1520).
>>>>
>>>> Althought I'm still with my fingers crossed, I can tell the good
>>>> news are that 2.6.21.5-rt19 (and -rt20) does behave far better now
>>>> on the very same box.
>>>>
>>> Yes, it works much better indeed...
>>>
>>> Ingo: is there a place where I can read about the changes in different
>>> rtxx releases? What is new/better/fixed in rt20? (I see scheduler
>>> stuff in a diff from rt19 to rt20 but I don't really know what it
>>> means).
>>>
>> and rt18 was a -rt-only NOHZ fix, that bug got introduced in rt11 when
>> CFS was merged.
>>
>> i _think_ Rui might have seen two separate problems. Perhaps by the time
>> we fixed the first problem (which Rui saw since -rt2) we introduced the
>> other one via -rt11 - which then got fixed in -rt19.
>>
>
> Ahh, CFS is now part of rt, I was obviously not paying attention... I'm
> really trying to provide a "stable" rt kernel for audio usage and
> including another subsystem into rt is - IMHO - not going to help.
> What's the chance of splitting things?
>
>
>> btw., we'd love to get more feedback regarding CFS. CFS is a completely
>> new scheduler for Linux.
>>
>
> Then I'd rather have it separate from rt.
>
>
>> It has a design centered around keeping
>> application latencies down, so it is ultimately real-time friendly, and
>> it should also make things work better for desktop-ish and audio-ish
>> stuff as well. (even under SCHED_OTHER)
>>
>
> Maybe this is CFS related? (tail of a thread in the Planet CCRMA mailing
> list):
>
> On Sun, 2007-07-08 at 15:26 -0400, Hector Centeno wrote:
>
>> Ok, so just to confirm, that 2.6.21-0182.rt19.1.fc7.ccrmart works fine
>> on my desktop but on my laptop it makes Firefox and Tomboy to crash.
>> On the same laptop using 2.6.21-0182.rt17.1.fc7.ccrmart there is no
>> problem.
>>
>> Cheers,
>>
>> Hector
>>
>>
>> On 7/7/07, Hector Centeno <hcengar@gmail.com> wrote:
>> Hi Fernando,
>>
>> I do have Flash installed but for me Firefox crashes when
>> trying to
>> access gmail (which AFAIK doesn't use Flash, does it?). Right
>> now
>> Firefox is frozen and I'm typing this email using Konkeror (in
>> Gnome).
>> This is ps' output:
>>
>> hector 3595 1.1 2.2 194352 46336 ? D 16:25
>> 0:03
>> /usr/lib/firefox-2.0.0.4/firefox-bin
>>
>> I think the problem is not present in my Desktop but I have to
>> double
>> check. In the same laptop using the stock fedora kernel both
>> Tomboy
>> and Firefox work fine. My laptop has a centrino duo processor,
>> 2 gigs
>> of ram and the Inte GMA950 graphics chip.
>>
>> Hector
>>
>
> I managed to completely hang firefox (fc7) with flash 9 installed
> (unkillable even with -9).

Firefox with flash 9 does not work good , there are a lot bugs reported
about ( just google ) and it hangs on vanilla or
whatever other kernels as well. Not only Firefox but also Swiftfox,
Opera, Epiphany etc.

The most time Firefox dies when you use flash 9 and close a window or a tab.

> Does not seem to happen with flash 7.

Yes flash 7 is fine.

> Have
> not tried yet with gmail and flash uninstalled. I'll try to strace it to
> see when/why it hangs.
>
>
> -- Fernando
>
>
>
>> So it would be nice if you could keep an extra eye on any scheduling
>> artifacts or regressions, and make sure your favorite workload is still
>> handled by the Linux scheduler in the utmost best way. I'd like to hear
>> about any sort of "scheduling behavior / interactivity" regression you
>> might see, relative to the vanilla kernel. Or if you can see no such
>> problems then a line of "it works as well as the previous scheduler" is
>> important info to us too. Thanks!
>>
>
>
>


Regards,

Gabriel C
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