[gpfsug-discuss] bizarre performance behavior - prefetchThreads

Marc A Kaplan makaplan at us.ibm.com
Fri Apr 21 13:58:26 BST 2017


Seems counter-logical, but we have testimony that you may need to reduce 
the prefetchThreads parameter.
Of all the parameters, that's the one that directly affects prefetching, 
so worth trying.

 Jan-Frode Myklebust wrote: ...Digging further I found that 
reducing prefetchThreads from default=72 to 32 also fixed it, while 
leaving maxMBpS at 10000. Can now also read at 3,2 GByte/s....

I can speculate that having prefetchThreads to high may create a 
contention situation where more threads causes overall degradation in 
system performance.



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gpfsug.org/pipermail/gpfsug-discuss_gpfsug.org/attachments/20170421/8dd9ff3d/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 21994 bytes
Desc: not available
URL: <http://gpfsug.org/pipermail/gpfsug-discuss_gpfsug.org/attachments/20170421/8dd9ff3d/attachment-0002.gif>


More information about the gpfsug-discuss mailing list