Messages in this thread | | | Subject | Re: [PATCH] proc: Add RLIMIT_RTTIME to /proc/<pid>/limits | From | Peter Zijlstra <> | Date | Thu, 28 Feb 2008 16:50:21 +0100 |
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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.
> Also, is this limit per-thread or per-process? I assume the latter -- > but can you confirm please.
Per process. Requests have been made to allow for per thread, but rlimits are not.
Its really not meant as a fine-grained deadline notification mechanism, we have posix timers for that, but as a watchdog to ensure we behave 'well'.
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