Messages in this thread | | | Date | Fri, 29 Feb 2008 21:39:14 +0100 | From | Ingo Molnar <> | Subject | Re: Scheduler broken? sdhci issues with scheduling |
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* 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
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