Can you please throw light on what kind of bottlenecks that may impact perf.... Thanks! On Sat, Apr 3, 2010 at 4:20 AM, Keld Simonsen <keld@xxxxxxxxxx> wrote: > On Fri, Apr 02, 2010 at 02:37:40PM -0700, Learner Study wrote: >> I have seen ~180MB/s RAID5 performance with 4 disks...are you saying >> that I could achieve even higher if I have more number of disks (so >> instead of 3+1, try 6+1 or 9+1)? >> Logically, this sounds right but wanted to verify my thought process >> with you.... > > Yes, with more spindles you can generally expect more performance. > Beware of bottlenecks, tho. > > Best regards > keld > >> Thanks! >> >> On Fri, Apr 2, 2010 at 2:14 PM, Keld Simonsen <keld@xxxxxxxxxx> wrote: >> > On Fri, Apr 02, 2010 at 10:55:53AM -0700, Learner Study wrote: >> >> Hi Keld: >> >> >> >> Thanks for your email... >> >> >> >> 1. Can you pls point me to this benchmark (which shows 500MB/s)? I >> >> would like to know which CPU, HDDs and kernel version used to achieve >> >> this... >> > >> > http://home.comcast.net/~jpiszcz/20080329-raid/ >> > 496843 KB/s for sequential input with 10 raptor drives >> > There probably is an email in the archives with more info on the >> > test. >> > >> >> 2. Secondly, I would like to understand how raid stack (md driver) >> >> scales as we add more cores...if single core gives ~500MB/s, can two >> >> core give ~1000MB/s? can four cores give ~2000MB/s? etc.... >> > >> > No, the performance is normally limited by the number of drives. >> > I would not wsay that more cores woould do a little >> > but it would be in the order of 1-2 % I think. >> > This is also dependent on wheteher the code actually runs threaded. >> > I doubt it.... >> > >> > best regard >> > keld >> > >> >> >> >> Thanks for your time. >> >> >> >> On Fri, Apr 2, 2010 at 4:05 AM, Keld Simonsen <keld@xxxxxxxxxx> wrote: >> >> > On Thu, Apr 01, 2010 at 08:07:25PM -0700, Learner Study wrote: >> >> >> Hi Keld: >> >> >> >> >> >> Do we have raid5/6 numbers for linux on any multi-core CPU? Most of >> >> >> the benchmarks I have seen on wiki show raid5 perf to be ~150MB/s with >> >> >> single core CPUs. How does that scale with multiple cores? Something >> >> >> like intel's jasper forest??? >> >> > >> >> > I have not checked if the benchmarks were on multi core machines. >> >> > It should not matter much if there were more than one CPU, but >> >> > of cause it helps a little. bonnie++ test reports cpu usage, and this >> >> > is not insignificant, say in the 20 -60 % range for some tests, >> >> > but nowhere near a bottleneck. There was one with a raid5 performance >> >> > seq read of about 500 MB/s with 36 % cpu utilization, so it is >> >> > definitely possible to come beyound 150 MB/s. The speed is largely >> >> > dependent on number of disk drives you employ. >> >> > >> >> > >> >> >> If available, can u pls point me to numbers with multi-core CPU? >> >> > >> >> > I dont have such benchmarks AFAIK. But new benchmarks are always welcome, >> >> > so please feel free to submit your findings. >> >> > >> >> > Best regards >> >> > keld >> >> > >> >> >> Thanks! >> >> >> >> >> >> On Wed, Mar 31, 2010 at 1:15 PM, Keld Simonsen <keld@xxxxxxxxxx> wrote: >> >> >> > On Wed, Mar 31, 2010 at 12:42:57PM -0700, Learner Study wrote: >> >> >> >> Hi Linux Raid Experts: >> >> >> >> >> >> >> >> I was looking at following wiki on raid perf on linux: >> >> >> >> >> >> >> >> https://raid.wiki.kernel.org/index.php/Performance >> >> >> >> >> >> >> >> and notice that the performance numbers are with 2.6.12 kernel. >> >> >> >> >> >> >> >> Do we perf numbers for: >> >> >> >> - latest kernel (something like 2.6.27 / 2.6.31) >> >> >> >> - raid 5 and 6 >> >> >> >> >> >> >> >> Can someone please point me to appropriate link? >> >> >> > >> >> >> > The link mentioned above has a number of other performance reports, for other levels of the kernel. >> >> >> > Anyway you should be able to get comparable results for newer kernels, the kernel has not become >> >> >> > slower since 2.6.12 on RAID. >> >> >> > >> >> >> > best regards >> >> >> > Keld >> >> >> > >> >> >> -- >> >> >> 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 >> >> > >> >> -- >> >> 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 >> > >> -- >> 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 > -- 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
