Attached is .config for 2.6.27 kernel. Its mips64....Do you see anything wrong with it? I don't yet access to my m/c for 2.6.21...would email that later. Any feedback... Thanks! On Wed, Sep 16, 2009 at 1:21 AM, Majed B. <majedb@xxxxxxxxx> wrote: > 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. >
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