[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

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cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-367907988
 
 
   i don?t set the environment variable. I doubt it would
   work even if i did, from within the code. So there?s nothing I can do,
   then, right? User would need to set?
   
   I recall dumping the default behavior of KMP and i remember it showing that
   the OMP threads were indeed staggered as in your picture.  I?ll check again.
   
   On Thu, Feb 22, 2018 at 8:13 PM PatricZhao  wrote:
   
   > Normally, we set KMP_AFFILITY with OMP_NUM_THREADS together.
   > And when the OMP threads are invoked, it will be used.
   >
   > ?
   > You are receiving this because you were mentioned.
   > Reply to this email directly, view it on GitHub
   > 
,
   > or mute the thread
   > 

   > .
   >
   


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[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

[GitBox]

cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-367901652
 
 
   how to set this programmatically? i?d imagine that by the time this code
   executes, the omp library may have already checked the environment variable
   (as it does with OMP_NUM_THREADS)? or can it be set at any time?
   
   On Thu, Feb 22, 2018 at 4:49 PM PatricZhao  wrote:
   
   > Thanks, @cjolivier01 , I mean we set this
   > environment in the code as OMP_NUM_THREADS.
   >
   > Actually, this setting is useful when hyperthreading is ON and we only
   > want to run each thread in a physical core as below picture shown
   > (KMP_AFFINITY=granularity=fine,compact,1,0).
   >
   > So, this environment will guide how to map thread into the physical core.
   > https://software.intel.com/en-us/node/522691
   >
   > [image: guid-80fda344-d8c1-4fea-b268-94f685d19c4c-imageid
   > 0abe3e2e-7a5a-4072-b22f-da7f72eb9a18]
   > 

   > *KMP_AFFINITY=granularity=fine,compact,1,0*
   >
   > ?
   > You are receiving this because you were mentioned.
   > Reply to this email directly, view it on GitHub
   > 
,
   > or mute the thread
   > 

   > .
   >
   


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[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

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cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-367727571
 
 
   Can you also explain what these settings do? I know it's in a manual 
somewhere, but from your perspective, what does it do and why is that best?


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[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

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cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-367727199
 
 
   Are you saying I should set the environment variable in the code:
   KMP_AFFINITY=granularity=fine,noduplicates,compact,1,0
   ?


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[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

[GitBox]

cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-367727199
 
 
   Are you sauing I should set the environment variable in the code:
   KMP_AFFINITY=granularity=fine,noduplicates,compact,1,0
   ?


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[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

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cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-367726497
 
 
   I am only vaguely familiar with the KMP stuff.  Can you please elaborate?  
Are you saying that it is slower now in some situations?


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[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

[GitBox]

cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-364226874
 
 
   yeah, that's probably the best place for it.  nice work!


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[GitHub] cjolivier01 commented on issue #9744: Performance regression when OMP_NUM_THREADS environment variable is not set

[GitBox]

cjolivier01 commented on issue #9744: Performance regression when 
OMP_NUM_THREADS environment variable is not set
URL: 
https://github.com/apache/incubator-mxnet/issues/9744#issuecomment-364201100
 
 
   Thank you for the excellent detailed explanation.
   
   Just curious, what is meant by "regression" in this context?  Was there some 
point in the past where OMP threads were set to optimum in all threads?
   
   Is your solution calling omp_set_num_threads() from CPUWorker?


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