Out of curiosity, why are you upgrading the kernel? Are you after a certain feature offered by the new kernel? If not, roll back to a kernel version where you don't face performance drops. On Tue, Oct 13, 2009 at 2:06 PM, mark delfman <markdelfman@xxxxxxxxxxxxxx> wrote: > A little more information which I ‘think’ seems to point at MD..... > > Creating an EXT3 FS on an MD RAID also shows a circa 50% performance drop. > We have tried a multitude of RAID options (raid6/0 various chunks etc). > > Using a hardware based raid XFS / EXT3 shows no performance drop > (although the hardware raid is significantly slower than MD in the > first place) > > We are happy to keep testing and offering anything that could be > useful, we are just a little stuck thinking of anything else to do.... > > > > > On Tue, Oct 13, 2009 at 2:33 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: >> On Mon, Oct 12, 2009 at 05:58:20PM +0100, mark delfman wrote: >>> Hi... in recent tests we are seeing a 50% drop in performance from >>> XFS>MD on a 2.6.30 kernel (compared to a 2.6.28 kernel) >>> >>> In short: Performance to MD0 direct = circa 1.7GBsec (see below), via >>> xfs circa 850MBsec. On previous system (2.6.28) there was no drop in >>> performance (in fact often an increase). >>> >>> I am hopefully that this is simply a matter of barriers etc on the >>> newer kernel and MD, but we have tried many options and nothing seems >>> to change this so would very much appreciate advice. >> >> Did barrier support for RAID0 got introduced in 2.6.30? >> >> > -- > 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
