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Date: Tue, 02 Sep 2008 13:06:25 +0530 From: Balbir Singh <balbir@...ux.vnet.ibm.com> To: Peter Zijlstra <a.p.zijlstra@...llo.nl> CC: Spencer Candland <spencer@...ehost.com>, dmitry.adamushko@...il.com, mingo@...e.hu, linux-kernel@...r.kernel.org Subject: Re: Still seeing decreasing stime/utime Peter Zijlstra wrote: > On Sat, 2008-08-30 at 19:25 +0530, Balbir Singh wrote: >> * Peter Zijlstra <a.p.zijlstra@...llo.nl> [2008-08-30 13:27:36]: >> >>> On Sat, 2008-08-30 at 11:26 +0530, Balbir Singh wrote: >>>> Spencer Candland wrote: >>>>>> Here is an experimental patch (I've just compiled and booted a machine >>>>>> with it, I am unable to reproduce your problem), could you please test >>>>>> it for me and see if it helps solve the problem >>>>> Looks like this fixed it. I have been testing this for the last 16 >>>>> hours and everything is looking good. >>>>> >>>> Excellent! Ingo, Peter, do you like the patch? If so, could you please pick it >>>> up Ingo. I think we should even push the fix to stable releases. >>> Looks good, except for the issue you yourself earlier raised, a few of >>> those functions looks too large to be inlined. >>> >> Here's the updated revision with task_*time functions moved to sched.c >> and inlining removed, except for task_gtime(). I've compiled and >> booted a machine (x86_64) with this patch applied. >> >> Reported-by: spencer@...ehost.com >> >> Spencer reported a problem where utime and stime were going negative despite >> the fixes in commit b27f03d4bdc145a09fb7b0c0e004b29f1ee555fa. The suspected >> reason for the problem is that signal_struct maintains it's own utime and >> stime (of exited tasks), these are not updated using the new task_utime() >> routine, hence sig->utime can go backwards and cause the same problem >> to occur (sig->utime, adds tsk->utime and not task_utime()). This patch >> fixes the problem >> >> TODO: using max(task->prev_utime, derived utime) works for now, but a more >> generic solution is to implement cputime_max() and use the cputime_gt() >> function for comparison. >> >> Comments? >> >> Signed-off-by: Balbir Singh <balbir@...ux.vnet.ibm.com> > > Thanks Balbir! > > Acked-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> Ingo, could you please pick this one. -- Thanks, Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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