[LLVMdev] google heap profile

[Chandler Carruth]

On Fri, Nov 11, 2011 at 11:45 AM, reed kotler <rkotler at mips.com> wrote:

> **
> On 11/11/2011 11:39 AM, Chandler Carruth wrote:
>
> On Fri, Nov 11, 2011 at 11:36 AM, reed kotler <rkotler at mips.com> wrote:
>
>> Is anybody using the google heap profiler to analyze clang/llvm ??
>>
>> http://google-perftools.googlecode.com/svn/trunk/doc/heapprofile.html
>>
>> If so, do you know how to modify the build scripts to enable that.
>>
>> Tia.
>
>
>  I have tried to use this in the past without terribly much success.
> Instead, I usually use Valgrind to analyze the allocation patterns:
> http://valgrind.org/docs/manual/ms-manual.html
>
> I've been using valgrind too. It seems to work fine.
>
> I need to independently validate some numbers though because the answer
> has big implications for some planning we are doing.
>

In the past I have use the Google perf tools by using LDPRELOAD to inject
them into the running binary.

Note that the subprocess-ing can impact things, you need to drop down to
the cc1 invocation first.

Still, I have found that the heap profiling in these tools is strictly
inferior to massif. I'd trust it. There are lots of flags you can give to
massif to cause it to be very very accurate despite being quite slow. Do
those help?

You can also look at the '-print-stats' option (or something like that)
which prints out internal allocation stats for various significant parts of
Clang, and might be able to correlate the two to gain confidence.
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