Hi Majed: I have compiled by kernel. 2.6.27 config has lot of new stuff - port multiplier/Sil3124/3132 support etc. I see following SCHED/DMA related differences: CONFIG_IOSCHED_AS CONFIG_IOSCHED_CONFIG CONFIG_CLASSIS_RCV CONFIG_SCSI_DMA Is there anything else that I missed? Thanks for ur time and help! On Wed, Sep 16, 2009 at 9:12 PM, Majed B. <majedb@xxxxxxxxx> wrote: > Attached is the diff file between the config files of kernels 21 & 27. > > I see a lot of DMA changes and schedulers. > > I've asked you before if you compiled your own kernel or do you use > unmodified distro kernels? > > If you compile your own, then you could import the 21 config to the 27 > compile process and then compare the performance of the two kernels. > > 2009/9/17 Linux Raid Study <linuxraid.study@xxxxxxxxx>: >> Hi: >> >> I tried to change the Raid5 stripe cache size by doing >> "echo 262144 > /sys/block/md0/md/stripe_cache_size" >> But if I do "cat /sys/block/md0/md/stripe_cache_size", it still shows 1024! >> >> Can someone please suggest how to increase stripe cache size? >> >> thanks! >> >> >> 2009/9/10 Keld Jørn Simonsen <keld@xxxxxxxx>: >>> Hi >>> >>> There is some data on raid5 performance (and other raid types) at our >>> wiki at: http://linux-raid.osdl.org/index.php/Performance >>> >>> When you have something you want to share with others, then we can add >>> your info to the data there, either by a URL or by direct inclusion in >>> the wiki. >>> >>> best regards >>> keld >>> >>> On Wed, Sep 09, 2009 at 06:45:31PM -0700, Linux Raid Study wrote: >>>> 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 >>> >> > > > > -- > 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
