Messages in this thread | | | Date | Fri, 11 Apr 2008 09:38:09 +0200 | From | "Michael Kerrisk" <> | Subject | Re: [PATCH] proc: Add RLIMIT_RTTIME to /proc/<pid>/limits |
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On Thu, Feb 28, 2008 at 5:50 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote: > > On Thu, 2008-02-28 at 16:44 +0100, Michael Kerrisk wrote: > > Peter, > > > > Thanks for the text. > > > > On Thu, Feb 28, 2008 at 4:21 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote: > > > > > > On Thu, 2008-02-28 at 16:12 +0100, Michael Kerrisk wrote: > > > > Peter, > > > > > > > > Could you please provide some text describing RLIMIT_RTTIMEfor the > > > > getrlimit.2 man page. > > > > > > The rlimit sets a timeout in [us] for SCHED_RR and SCHED_FIFO tasks. > > > This time is measured between sleeps, so a schedule in RR or a > > > preemption in either is not a sleep - the task needs to be dequeued and > > > enqueued for the timer to reset. > > > > Just to clarify: sleep here means a call to some blocking syscall > > (e.g., nanosleep(), read(), select(), etc.), right? Is there anything > > else that falls under the category of "sleep"? What about a call to > > sched_yield() where the process explicitly lets go of the CPU? > > Yes, and yes, others would be blocking on futexes and the like.
Peter,
I've been testing this patch. Above you seemed to be saying that doing a sched_yield() would be equivalent to a sleep, causing the rt counter to be reset to zero. Howver, the results I'm seeing suggest that a sched_yield() does not cause the counter to be reset to zero (i.e., despite calling sched_yield() at frequent intervals, the process still encounters the RLIM_RTTIME soft limit and gets SIGXCPU). Can you comment?
Cheers,
Michael -- Michael Kerrisk Maintainer of the Linux man-pages project http://www.kernel.org/doc/man-pages/ Want to report a man-pages bug? Look here: http://www.kernel.org/doc/man-pages/reporting_bugs.html
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