Re: Reason for md raid1 max_sectors_kb limited to 127?

[Sebastian Riemer <sebastian.riemer@xxxxxxxxxxxxxxxx>]

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.

Cheers,
Sebastian
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