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. Any ideas... 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. ÂAnd 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
