Mikulas Patocka <mpatocka@xxxxxxxxxx> writes: > On Tue, 18 Sep 2012, Jeff Moyer wrote: > >> Mikulas Patocka <mpatocka@xxxxxxxxxx> 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 >> > 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? There is no good reason for it. Since I was able to show some differences in performance, I didn't see the need to scale beyond 4. I can certainly bump the count up if/when that becomes interesting. Cheers, Jeff -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
