IPI Benchmark Data?

[Sepherosa Ziehau]

On Wed, Aug 3, 2016 at 10:27 AM, Alex Merritt <merritt.alex at gmail.com> wrote:
> Hello all,
>
> I saw 4.6 was released, great! From the release notes:
>
>> SMP performance was already very good. As part of the NVMe driver work we
>> revamped the buffer cache subsystem and a number of other I/O related paths,
>> further reducing lock contention and IPI signalling overheads.
>
> Was the IPI signaling cost reduced due to the cache improvements, or were
> there other updates specifically for the IPI subsystem to improve the
> performance?
>
> Is there any available data illustrating or describing the IPI latencies,
> overheads, sustained throughput, or other characteristics on DF across cores
> and sockets on SMP systems?

There are set of sysctls to test IPI latency:

debug.ipiq.latency_test
debug.ipiq.latencyX

test/sysperf/ipitest uses these sysctls to test IPI latency in various
MWAIT C-states.

Thanks,
sephe

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