Would you mind attaching both kernel config files and emailing them? Also, did you compile your own kernels or do you run certain images? On Wed, Sep 16, 2009 at 11:19 AM, Majed B. <majedb@xxxxxxxxx> wrote: > I've run my own tests a few days back on a machine I have, but I > haven't compared the results to tests on the same machine with older > kernels. > > I have attached my machine's kernel config file. > > I run an Ubuntu 9.04 Server - Kernel 2.6.28-15-server. > > On Wed, Sep 16, 2009 at 11:10 AM, Linux Raid Study > <linuxraid.study@xxxxxxxxx> wrote: >> Yes - as far as Raid/disk-controller stuff is concerned, they are >> same. BTW, is there anything specific you would like me to check. >> >> Have you done similar tests? Do you see any perf drop? >> >> Thanks! >> >> On Wed, Sep 16, 2009 at 1:06 AM, Majed B. <majedb@xxxxxxxxx> wrote: >>> Did you compare both kernel's config files to see whether these >>> kernels have been compiled with different options? >>> >>> On Wed, Sep 16, 2009 at 10:57 AM, Linux Raid Study >>> <linuxraid.study@xxxxxxxxx> wrote: >>>> Hi Majed, All: >>>> >>>> I'm using the default scheduler with 2.6.21 and 2.6.27...do you know >>>> if there is any difference? >>>> >>>> I rechecked the perf today - everything (i.e. disks, disk controller >>>> etc) remaining the same, I see around 45MB/s difference in performance >>>> when I change kernel from 2.6.21 to 2.6.27. I issue following cmd to >>>> see performance: >>>> hdparm -t /dev/md0 >>>> >>>> FYI...I'm using Seagate HDDs (7200 RPM) with RocketRaid 2310 controller. >>>> >>>> Any ideas...I have tried blockdev readahead option and it helps but >>>> still not enough... >>>> >>>> Thanks a lot! >>>> >>>> On Wed, Sep 9, 2009 at 4:52 PM, 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. >>> >> > > > > -- > 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
