On 01/24/2014 11:09 PM, Andreas Dilger wrote:

I think the ext4 block groups are locked with the blockgroup_lock that has about the same number of locks as the number of cores, with a max of 128, IIRC.  See blockgroup_lock.h. 

While there is some chance of contention, it is also unlikely that all of the cores are locking this area at the same time.  

Cheers, Andreas

Thanks Andreas for the suggestion. Will try that versus adding just a new private spinlock array in mbcache and compare the performance.

Thanks,
Mak.