On Mon, 2010-03-29 at 11:10 -0400, Greg Freemyer wrote:
> On Mon, Mar 29, 2010 at 2:25 AM, Keith Mannthey <kmannth@xxxxxxxxxx> wrote:
> >
> >
> > After 2.6.30 I am seeing large performance regressions on a raid setup.
> > I am working to publish a larger amount of data but I wanted to get some
> > quick data out about what I am seeing.
> >
>
> Is mdraid involved?
>
> They added barrier support for some configs after 2.6.30 I believe.
> It can cause a drastic perf change, but it increases reliability and
> is "correct".
lvm and device mapper are is involved. The git bisect just took me to:
374bf7e7f6cc38b0483351a2029a97910eadde1b is first bad commit
commit 374bf7e7f6cc38b0483351a2029a97910eadde1b
Author: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Mon Jun 22 10:12:22 2009 +0100
dm: stripe support flush
Flush support for the stripe target.
This sets ti->num_flush_requests to the number of stripes and
remaps individual flush requests to the appropriate stripe devices.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
:040000 040000 542f4b9b442d1371c6534f333b7e00714ef98609 d490479b660139fc1b6b0ecd17bb58c9e00e597e M drivers
This may be correct behavior but the performance penalty in this test
case is pretty high.
I am going to move back to current kernels and starting looking into
ext4/dm flushing.
Thanks,
Keith Mannthey
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