Re: xfs > md 50% write performance drop on .30+ kernel?

["Majed B." <majedb@gmail.com>]

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@googlemail.com> 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@infradead.org> 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@vger.kernel.org
> 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@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html