I build/compile my own kernel.. Have you done any benchmarks for Read RAID5 perf? Thanks! On 9/9/09, Majed B. <majedb@xxxxxxxxx> wrote: > Well, that's my point. To make sure that your kernels are identical in > options, compare the .config files found in /usr/src/linux-<version> > > You may find changes and differences in areas like bluetooth, > wireless, ...etc. These don't matter. > > Did you compile your own kernel, or are you using one compiled for a > specific distro? > > On Thu, Sep 10, 2009 at 4:17 AM, Linux Raid > > Study<linuxraid.study@xxxxxxxxx> wrote: > > Yes - the setup is the same. The only thing that changes is the kernel. > > > > I have 4 HDDs (2 from WD VelociRaptor 150GB/10k RPM and 2 from Seagate > > 320GB/7.2k RPM). The HDDs are connected using two Silicon Image SATA > > controllers (Sil3132) connected to my host using PCIe. > > > > I use the default kernel scheduling scheme. > > > > Thanks! > > > > On 9/9/09, Majed B. <majedb@xxxxxxxxx> wrote: > >> Are you sure you're using the same Kernel Scheduler on both kernels? > >> > >> Have you checked and verified that the same drivers are being loaded? > >> (IDE vs. AHCI -- proprietary drivers vs. open source) > >> > >> This is interesting! > >> > >> > >> On Thu, Sep 10, 2009 at 1:54 AM, Linux Raid > >> Study<linuxraid.study@xxxxxxxxx> wrote: > >> > Hello: > >> > > >> > I'm benchmarking RAID5 Read performance with 4 disks and notice perf > >> > drop when using kernel 2.6.27. > >> > The perf with 2.6.27 is 150MB/s whereas with kernel 2.6.21 (and same > >> > setup), the perf is 180MB/s/ > >> > > >> > > >> > > >> > Some of the tests I have done: > >> > 1. I ran experiments using iozone also but notice that READ perf with > >> > RAID5 in 2.6.27 is ~30% less as compared to 2.6.21. > >> > Write perf is similar but Read is an issue. > >> > > >> > 2. On 2.6.27, I played around with chunk size and blocksize parameters > >> > and got ~5% improvement but not much. I used following cmds: > >> > > >> > #mdadm --create /dev/md0 --level=5 --assume-clean --raid-devices=4 > >> > /dev/sda /dev/sdb /dev/sdc /dev/sdd --chunk=32 > >> > #mke2fs -b 4096 -E stride=8 /dev/md0 > >> > > >> > #time dd if=/dev/md0 of=/dev/null bs=94208 count=1024 > >> > > >> > > >> > Is this perf drop a known issue? Can someone please recommend some > >> > performance tuning tips? > >> > > >> > Thanks a lot for your time and help! > >> > >> > -- > >> > 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 > >> > > >> > >> > >> > >> -- > >> > >> Majed B. > >> > > > > > > > -- > > Majed B. > -- 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
