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SubjectRe: [RFC][PATCH 0/3] locking/mutex: Rewrite basic mutex
On 08/25/2016 11:43 AM, Peter Zijlstra wrote:
> On Tue, Aug 23, 2016 at 06:13:43PM -0700, Jason Low wrote:
>> I tested this patch on an 8 socket system with the high_systime AIM7
>> workload with diskfs. The patch provided big performance improvements in
>> terms of throughput in the highly contended cases.
>>
>> -------------------------------------------------
>> | users | avg throughput | avg throughput |
>> | without patch | with patch |
>> -------------------------------------------------
>> | 10 - 90 | 13,943 JPM | 14,432 JPM |
>> -------------------------------------------------
>> | 100 - 900 | 75,475 JPM | 102,922 JPM |
>> -------------------------------------------------
>> | 1000 - 1900 | 77,299 JPM | 115,271 JPM |
>> -------------------------------------------------
>>
>> Unfortunately, at 2000 users, the modified kernel locked up.
>>
>> # INFO: task reaim:<#> blocked for more than 120 seconds.
>>
>> So something appears to be buggy.
> So with the previously given changes to reaim, I get the below results
> on my 4 socket Haswell with the new version of 1/3 (also below).
>
> I still need to update 3/3..
>
> Note that I think my reaim change wrecked the jobs/min calculation
> somehow, as it keeps increasing. I do think however that the numbers are
> comparable between runs, since they're wrecked the same way.

The performance data for the 2 kernels were roughly the same. This was
what I had been expecting as there was no change in algorithm in how the
slowpath was being handled. So I was surprised by Jason's result
yesterday showing such a big difference.

Cheers,
Longman

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