[LLVMdev] multithreaded performance disaster with -fprofile-instr-generate (contention on profile counters)

[Xinliang David Li]

On Thu, Apr 17, 2014 at 10:58 AM, Duncan P. N. Exon Smith <
dexonsmith at apple.com> wrote:

>
> On 2014-Apr-17, at 10:38, Xinliang David Li <xinliangli at gmail.com> wrote:
>
> >
> > Another idea is to use stack local counters per function -- synced up
> with global counters on entry and exit. the problem with it is for deeply
> recursive calls, stack pressure can be too high.
>
> I think they'd need to be synced with global counters before function
> calls as well, since any function call can call "exit()".
>

right -- but it might be better to handle this in other ways. For instance
a stack of counters for each frames is maintained. At exit, they are
flushed in a batch. Or simply ignore it in case of program exit .

David
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