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

[Wei Mi via llvm-commits]

Ok, I will try it out using the multithreaded benchmark as well.

On Thu, Jun 18, 2020 at 11:27 AM Rong Xu <xur at google.com> wrote:

> BTW, I used google internal benchmarks that are highly threaded.  I don't
> remember the exact numbers. But should be more than 10% runtime increase.
>
> On Thu, Jun 18, 2020 at 11:17 AM Rong Xu <xur at google.com> wrote:
>
>> Ok, got it . That's probably a single thread program. Instrumentation
>> overhead is low.
>>
>> On Thu, Jun 18, 2020 at 11:13 AM Wei Mi <wmi at google.com> wrote:
>>
>>>
>>>
>>> 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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