On 05/07/2012 05:33 PM, Sebastian Riemer wrote:
On 07/05/12 16:47, Bernd Schubert wrote:
On 05/07/2012 04:44 PM, Roberto Spadim wrote:
could check if it have any performace increase? maybe i consider
upgrading my kernel to get more performace inn raid1
Depends on your hardware. Hardware that can handle small IO sizes, such
as common hard disks usually don't have problems with 512KB IOs. But if
you should use software on top of hardware raid large IOs might be very
important (again depends on the hw-raid vendor then).
Cheers,
Bernd
O.K., I've also tested 3.2.16 and there the problem still exists.
Bernd pinpointed me to commit b1bd055d397e09f99dcef9b138ed104ff1812fcb
(block: Introduce blk_set_stacking_limits function).
After cherry-picking it on 3.2.16 it worked. Tomorrow I'll test the
performance impact and verify it by block tracing.
You might want to check IO sizes with my a patched blkiomon (blktrace).
I added a mode to make the IO table more verbose about actual io sizes.
I always wanted to further improve it and to send patches upstream, but
so far didn't find time for that.
http://www.pci.uni-heidelberg.de/tc/usr/bernd/downloads/blktrace/
Cheers,
Bernd
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