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, and can be preempted by the RTOS; CPU k tries to acquire the lock before hlt, i.e. with hw flags disabled, 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
