Messages in this thread | | | Date | Fri, 28 May 2010 11:11:24 -0700 | Subject | Re: [PATCH] sched_clock: Provide local_clock() and improve documentation | From | Chad Talbott <> |
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On Fri, May 28, 2010 at 6:13 AM, Peter Zijlstra <peterz@infradead.org> wrote: > + * local_clock() -- is cpu_clock() on the current cpu.
Pretty sure this should read, "is cpu_clock() on *some* cpu," since there is no guarantee in a preemptible kernel that local_clock() returns on the same CPU that it was called from. The caller has to do the preempt protection itself.
The function could be written as follows (thanks Salman Qazi):
u64 local_clock(unsigned int *where) { u64 clock; unsigned long flags;
local_irq_save(flags); *where = smp_processor_id(); clock = sched_clock_cpu(*where); local_irq_restore(flags);
return clock; }
but I don't see the utility of the resulting routine.
Chad -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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