Messages in this thread | | | Date | Mon, 13 Feb 2012 13:34:10 +0800 | From | Yong Zhang <> | Subject | Re: [RFC] Extend mwait idle to optimize away IPIs when possible |
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On Fri, Feb 10, 2012 at 06:11:58PM -0800, Venki Pallipadi wrote: > On Fri, Feb 10, 2012 at 11:19 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > On Mon, 2012-02-06 at 12:42 -0800, Venkatesh Pallipadi wrote: > >> smp_call_function_single and ttwu_queue_remote sends unconditional IPI > >> to target CPU. However, if the target CPU is in mwait based idle, we can > >> do IPI-less wakeups using the magical powers of monitor-mwait. > > > > So I was thinking, why not change native_smp_send_reschedule() and > > native_send_call_func_single_ipi() and keep the change entirely inside > > the arch? > > > > Ideally its only APIC/idle that know about this detail, the scheduler > > (or other consumers) really don't care about how the other cpu comes to > > run the callback. > > > > OK. Moving most of this into arch code will be cleaner. But, Yong > mentioned in this thread that he was looking to do something similar > on MIPS. So, we may end up with some code duplication though..
Yeah, most of the things could be shared. Such as the added logic when return from idle and the hooks into ttwu_queue_remote() and generic_exec_single().
BTW, I think we should also let the arch provide a wrapper for TIF_IPI_PENDING, such as tsk_ipi_pending().
Thanks, Yong > -- > 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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