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From: Ingo Molnar <mingo@elte.hu>
To: Simon Huggins <huggie@earth.li>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Scheduler broken? sdhci issues with scheduling
Date: Fri, 29 Feb 2008 21:39:14 +0100	[thread overview]
Message-ID: <20080229203914.GD27212@elte.hu> (raw)
In-Reply-To: <20080229193951.GI24533@paranoidfreak.co.uk>


* Simon Huggins <huggie@earth.li> wrote:

> Hi Ingo,
> 
> (please cc me again)
> 
> On Fri, Feb 29, 2008 at 02:34:33PM +0100, Ingo Molnar wrote:
> > * Simon Huggins <huggie@earth.li> wrote:
> > > [ Please Cc me on replies ]
> > > I had a bug with sdhci which Pierre Ossman looked at for me.
> > > In the end essentially the fix was to use HZ=1000 and nothing else. 
> > > Pierre seemed to think that this was a bug in the scheduler.
> > does the patch below help, even if you keep HZ=100? This doesnt look 
> > like a scheduler issue, it's more of a timer/timing issue. Different HZ 
> > means different msleep() results - and the mmc code does a loop of small 
> > msleep delays.
> 
> Thanks for looking at it.
> 
> I did tests with 2.6.24.3 with HZ=1000 and HZ=100 and as expected the
> latter didn't work.
> 
> > -------------->
> > ---
> >  drivers/mmc/core/core.h |    7 +------
> >  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> > Index: linux/drivers/mmc/core/core.h
> > ===================================================================
> > --- linux.orig/drivers/mmc/core/core.h
> > +++ linux/drivers/mmc/core/core.h
> > @@ -36,12 +36,7 @@ void mmc_set_timing(struct mmc_host *hos
> 
> >  static inline void mmc_delay(unsigned int ms)
> >  {
> > -	if (ms < 1000 / HZ) {
> > -		cond_resched();
> > -		mdelay(ms);
> > -	} else {
> > -		msleep(ms);
> > -	}
> > +	mdelay(ms);
> >  }
> 
> >  void mmc_rescan(struct work_struct *work);
> 
> That doesn't work.  I did a test with HZ=100 and this patch.  I've 
> attached the log as patch1-log.

> Anything else I can try?

so neither precise, nor imprecise timings help??

	Ingo

  reply	other threads:[~2008-02-29 20:39 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-29 11:52 Simon Huggins
2008-02-29 13:34 ` Ingo Molnar
2008-02-29 13:51   ` Ingo Molnar
2008-02-29 14:00     ` Ingo Molnar
2008-02-29 19:39       ` Simon Huggins
2008-02-29 20:39         ` Ingo Molnar [this message]
2008-03-01 12:42           ` Simon Huggins
2008-03-01 14:08             ` Pierre Ossman
2008-03-02 10:40 ` Pavel Machek
2008-03-02 18:04   ` Simon Huggins
2008-03-03 19:43   ` Pierre Ossman
2008-03-03 20:38     ` Pavel Machek
2008-03-03 21:05       ` Pierre Ossman
2008-03-13 21:17         ` Simon Huggins
2008-03-15 15:04           ` Pierre Ossman
2008-04-20 21:07             ` Simon Huggins

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