Philippe Gerum wrote: > Pierangelo Masarati wrote: >> Philippe Gerum wrote: >>> Pierangelo Masarati wrote: >>>> Dear ADEOS users, >>>> >>>> 2.6.25 seems to show abnormal latencies on hardware that showed good >>>> performances up to 2.6.24. We think we traced down the issue to x86's >>>> process_xx.c, which disappeared after regressing default_idle() to >>>> 2.6.24. The related changes are described in the attached patch. >>>> >>> This patch would badly break the runqueue statistics, and likely the Linux >>> scheduler tick engine too. >>> >>> Actually, the hunk in default_idle() seems useless, since co-kernel activity >>> should be accounted as Linux idle time anyway. Does this patch also fixes >>> the issue you tracked down? >> Dear Philippe, >> >> we'll try it. It will require some time to empirically let it run for a >> while to be sure. Usually, the weird latency effect occurs within half >> a hour, but we'd like to wait a little longer. >> >> Apart from not disturbing Linux, your fix should work, since it doesn't >> touch the hw flag. The problem with the patch is likely that: CPU i >> gets the seqlock after hlt, > > I don't see any seqlock in the idling code. Did you mean the spinlock in > sched_clock_idle_wakeup_event()? >
You likely refer to ktime_get_ts(); fortunately, we should not lock out interrupts. > and can be preempted by the RTOS; CPU k >> tries to acquire the lock before hlt, i.e. with hw flags disabled, > > Hw flags are still on actually -- local_irq_disable() won't switch them off. > > so it >> cannot be preempted by the RTOS. If the RTOS after preempting CPU i >> does a bit of work, the RTOS on CPU k is stalled until the RTOS finishes >> working on CPU i. > >> In any case, it is now running on two machines: a 32 and a 64 bit. I'll >> let you know. >> >> Sincerely, p. >> >> _______________________________________________ >> Adeos-main mailing list >> [email protected] >> https://mail.gna.org/listinfo/adeos-main >> > > -- Philippe. _______________________________________________ Adeos-main mailing list [email protected] https://mail.gna.org/listinfo/adeos-main
