Messages in this thread | | | Date | Tue, 18 Sep 2012 14:55:29 -0400 (EDT) | From | Mikulas Patocka <> | Subject | Re: [PATCH 0/4] Fix a crash when block device is read and block size is changed at the same time |
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On Tue, 18 Sep 2012, Jeff Moyer wrote:
> Mikulas Patocka <mpatocka@redhat.com> writes: > > > Hi Jeff > > > > Thanks for testing. > > > > It would be interesting ... what happens if you take the patch 3, leave > > "struct percpu_rw_semaphore bd_block_size_semaphore" in "struct > > block_device", but remove any use of the semaphore from fs/block_dev.c? - > > will the performance be like unpatched kernel or like patch 3? It could be > > that the change in the alignment affects performance on your CPU too, just > > differently than on my CPU. > > I'll give it a try and report back. > > > What is the CPU model that you used for testing? > > http://ark.intel.com/products/53570/Intel-Xeon-Processor-E7-2860-%2824M-Cache-2_26-GHz-6_40-GTs-Intel-QPI%29 > > Cheers, > Jeff
BTW. why did you use just 4 processes? - the processor has 10 cores and 20 threads (so theoretically, you could run 20 processes bound on a single numa node). Were the results not stable with more than 4 processes?
Mikulas
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