On Monday 09 March 2009, Heiko Carstens wrote: > On Sun, 8 Mar 2009 19:35:53 +0100 Frans Pop <elendil@xxxxxxxxx> wrote: > > On Sunday 08 March 2009, Heiko Carstens wrote: > > > Could you try the patch below? Hopefully it gives us some more > > > hints about how much the values are screwed up. > > > > stime: 2ee0 utime: 1f40 acct_timexpd: 4e20 > > But still we have a negative dtime. So I think all this happen because > cpu time accounting happens completely unlocked from interrupt context > but acct_update_integrals gets also called from process context with > interrupts enabled. > > So a possible explanation for this behaviour: > > between reading tsk->stime/task->utime and tsk->acct_timexpd an > interrupt happens which updates accouting values. This causes > acct_timexpd to be greater than the former stime + utime and also > explains why the printk shows values which fit together. > > I think the patch below should fix the bug: Thanks Heiko. With that patch I can no longer reproduce the problem with 2.6.27.19, so it looks good to me. I do wonder why no one else has hit this problem before. Could it be because the emulator is a relatively (very) slow system? When you create the final patch, please add my: Reported by: Frans Pop <elendil@xxxxxxxxx> Tested by: Frans Pop <elendil@xxxxxxxxx> And it should of course also be CCed to stable@. Hope the other two issues can be solved as smoothly :-P Cheers, FJP -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
