Thanks so much, Jingwang! We will definitely look into it.
Becky On Mon, Nov 19, 2012 at 10:22 PM, Zhang, Jingwang <jingwang.zh...@emc.com>wrote: > Hi All,**** > > ** ** > > Here is our use case, and we are using the BMI code in OrangeFS 2.8.6:**** > > **1. **Malloc a buffer and write something to it.**** > > **2. **Send the buffer using BMI routines.**** > > **3. **Free the buffer and goto step 1**** > > ** ** > > And here we found the following problem:**** > > We found that the messages captured using ibdump is corrupt in iteration > 2. It became a mixture of data from iteration 1 and iteration 2.**** > > ** ** > > Here is some analysis we did:**** > > We noticed that when the data corruption occurs, the buffer always point > to the same virtual address. And after checking with the BMI code, we found > that the memcache code will keep the buffer registered(to ibverbs) and use > virtual address to determine whether a registered buffer could be reused or > not later.**** > > ** ** > > However I think the memcache shouldn’t keep the buffer registered, because > that the user might free this buffer, and when the user did free and > re-allocate the buffer, there might be a false match which might lead to > data corruption.**** > > ** ** > > So at first, we tested the code with “define ENABLE_MEMCACHE 0” to disable > the memcache. And then the test passed, so it is proven that the data > corruption is caused by memcache. However, performance will be affected if > the memcache is disabled completely.**** > > ** ** > > Finally we formatted the attached patch to solve the problem. It fixes the > broken code in the clauses when memcache is disabled. And it deregister the > buffer whenever its use-count drops to 0 and register it when it is used > again.**** > > ** ** > > Please feel free to share your thoughts and comments. Thank you very much. > **** > > ** ** > > Best Regards,**** > > Jingwang.**** > > _______________________________________________ > Pvfs2-developers mailing list > Pvfs2-developers@beowulf-underground.org > http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers > > -- Becky Ligon OrangeFS Support and Development Omnibond Systems Anderson, South Carolina
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