linux-kernel - Re: [PATCH v6 00/10] Enable haltpoll on arm64

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Message-ID: <87v805qs4w.fsf@oracle.com>
Date: Mon, 12 Aug 2024 15:43:27 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: "Tomohiro Misono (Fujitsu)" <misono.tomohiro@...itsu.com>
Cc: 'Ankur Arora' <ankur.a.arora@...cle.com>,
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Subject: Re: [PATCH v6 00/10] Enable haltpoll on arm64


Tomohiro Misono (Fujitsu) <misono.tomohiro@...itsu.com> writes:

>> Subject: [PATCH v6 00/10] Enable haltpoll on arm64
>>
>> This patchset enables the cpuidle-haltpoll driver and its namesake
>> governor on arm64. This is specifically interesting for KVM guests by
>> reducing IPC latencies.
>>
>> Comparing idle switching latencies on an arm64 KVM guest with
>> perf bench sched pipe:
>>
>>                                      usecs/op       %stdev
>>
>>   no haltpoll (baseline)               13.48       +-  5.19%
>>   with haltpoll                         6.84       +- 22.07%
>
> I got similar results with VM on Grace machine (applied to 6.10).

Great. Thanks for testing.

> [default]
> # cat /sys/devices/system/cpu/cpuidle/current_driver
> none
> # perf bench sched pipe
> # Running 'sched/pipe' benchmark:
> # Executed 1000000 pipe operations between two processes
>
>      Total time: 23.832 [sec]
>
>       23.832644 usecs/op
>           41959 ops/sec
>
> [With "cpuidle-haltpoll.force=1" commandline]
> # cat /sys/devices/system/cpu/cpuidle/current_driver
> haltpoll
> # perf bench sched pipe
> # Running 'sched/pipe' benchmark:
> # Executed 1000000 pipe operations between two processes
>
>      Total time: 6.340 [sec]
>
>        6.340116 usecs/op
>          157725 ops/sec
>
> Tested-by: Misono Tomohiro <misono.tomohiro@...itsu.com>

Thanks!

--
ankur