[PATCH] D81981: [PGO] Supplement PGO profile with Sample profile

[Wei Mi via llvm-commits]

On Thu, Jun 18, 2020 at 10:49 AM Rong Xu <xur at google.com> wrote:

>
>
> On Wed, Jun 17, 2020 at 3:07 PM Wei Mi via Phabricator <
> reviews at reviews.llvm.org> wrote:
>
>> wmi added a comment.
>>
>> In D81981#2099070 <https://reviews.llvm.org/D81981#2099070>, @davidxl
>> wrote:
>>
>> > I think it is good to have an entry counter always, so that the profile
>> dump is more readable. Do you have data showing the instrumentation
>> overhead and profile size impact (clang and some large app)?
>>
>>
>> Yes, I tried clang. The instrumentation runtime overhead increases by
>> about 0.8%. The raw profile size increases by 1.8%. The zipped profile size
>> increases by 0.15%.
>> Right now in the patch, inserting entry counter is guarded by a flag with
>> default value being false.
>>
>> How did you test clang. This is for one file or for the whole clang?
> To me, 0.8% is close to nothing.
> My previous patch shows much more than this for a highly threaded program.
>

This is to use clang to compile a single large file as a test.



>
>> Repository:
>>   rL LLVM
>>
>> CHANGES SINCE LAST ACTION
>>   https://reviews.llvm.org/D81981/new/
>>
>> https://reviews.llvm.org/D81981
>>
>>
>>
>>
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