On Wed, 13 Apr 2011 11:21:52 -0700 Linux Raid Study <linuxraid.study@xxxxxxxxx> wrote: > Let me reword previous email... > > I tried to change stripe_cache_size as following and tried values > between 16 to 4096 > echo 512 > /sys/block/md0/md/stripe_cache_size > > But, I'm not seeing too much difference in performance. I'm running on > 2.6.27sh kernel. I wouldn't expect much difference. > > Any ideas... On what exactly? What exactly are you doing, what exactly are the results? What exactly don't you understand? Detail help. NeilBrown > > Thanks for your help... > > On Tue, Apr 12, 2011 at 12:36 PM, Linux Raid Study > <linuxraid.study@xxxxxxxxx> wrote: > > Hello Neil, > > > > For the benchmarking purpose, I've configured array of ~30GB. > > stripe_cache_size is 1024 (so 1M). > > > > BTW, I'm using Windows copy (robocopy) utility to test perf and I > > believe block size it uses is 32kB. But since everything gets written > > thru VFS, I'm not sure how to change stripe_cache_size to get optimal > > performance with this setup... > > > > Thanks. > > > > On Mon, Apr 11, 2011 at 7:51 PM, NeilBrown <neilb@xxxxxxx> wrote: > >> On Mon, 11 Apr 2011 18:57:34 -0700 Linux Raid Study > >> <linuxraid.study@xxxxxxxxx> wrote: > >> > >>> If I use --assume-clean in mdadm, I see performance is 10-15% lower as > >>> compared to the case wherein this option is not specified. When I run > >>> without --assume_clean, I wait until mdadm prints "recovery_done" and > >>> then run IO benchmarks... > >>> > >>> Is perf drop expected? > >> > >> No. And I cannot explain it.... unless the array is so tiny that it all fits > >> in the stripe cache (typically about 1Meg). > >> > >> There really should be no difference. > >> > >> NeilBrown > >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
