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

[Jonathan Roelofs]

if (counter_is_local)
   counter++
   if (counter > threshold)
     counter_is_local=false
else
   increment_thread_local_counter()

On 4/17/14, 9:39 AM, Kostya Serebryany wrote:
>
>
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> On Thu, Apr 17, 2014 at 8:37 PM, Jonathan Roelofs <jonathan at codesourcery.com
> <mailto:jonathan at codesourcery.com>> wrote:
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>     How about per-thread if the counter is hot enough?
>
>
> Err. How do you know if the counter is hot w/o first profiling the app?
>

-- 
Jon Roelofs
jonathan at codesourcery.com
CodeSourcery / Mentor Embedded