[PATCH] D36351: [lld][ELF] Add profile guided section layout

[Michael Spencer via llvm-commits]

On Thu, Feb 1, 2018 at 1:46 PM, Peter Collingbourne <peter at pcc.me.uk> wrote:

> These are the results that I previously got with chrome:
> https://bugs.chromium.org/p/chromium/issues/detail?id=759259#c10
>
> Peter
>

Thanks!

- Michael Spencer


>
>
> On Feb 1, 2018 18:41, "Michael Spencer" <bigcheesegs at gmail.com> wrote:
>
> On Thu, Feb 1, 2018 at 10:06 AM, Rafael Avila de Espindola <
> rafael.espindola at gmail.com> wrote:
>
>> Rafael Avila de Espindola <rafael.espindola at gmail.com> writes:
>>
>> I tested the patch by linking chromium.
>>
>> With the last version of the patch I can measure a small improvement in
>> L1-icache-load-misses. Somehow iTLB-load-misses seems to get worse:
>>
>>  Performance counter stats for './default-ld.lld @response.txt -o t
>> --no-threads' (20 runs):
>>
>>            279,008      iTLB-load-misses
>>             ( +-  0.36% )
>>         17,916,925      L1-icache-load-misses
>>              ( +-  0.19% )
>>
>>        1.165371143 seconds time elapsed
>>         ( +-  0.12% )
>>
>>
>>  Performance counter stats for './sorted-ld.lld @response.txt -o t
>> --no-threads' (20 runs):
>>
>>            289,396      iTLB-load-misses
>>             ( +-  0.77% )
>>         16,922,395      L1-icache-load-misses
>>              ( +-  0.18% )
>>
>>        1.166535009 seconds time elapsed
>>         ( +-  0.12% )
>>
>> Do you have a suggestion of an open source program that might benefit
>> more from this optimization?
>>
>> Cheers,
>> Rafael
>>
>
> I don't expect this patch to have a large impact on lld as its working set
> is rather small. Peter Collingbourne previously tested this patch on Chrome
> and got rather good results. He's already CCed, so I pinged him on IRC to
> see if he can chime in.
>
> - Michael Spencer
>
>
>
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