Hello, Mark.

Mark Lord wrote:
> Tejun Heo wrote:
>> Speed down rules were too conservative.  Adjust them a bit.
>>
>> * More than 10 timeouts can't happen in 5 minutes as command timeout
>>   is 30secs.  Lower the limit for rule #1 to 6.
>>
>> * 10 timeouts is too high for rule #3 too.  Lower it to 6.
>>
>> * SATAPI can benefit from falling back to PIO too.  Allow SATAPI
>>   devices to fall back to PIO.
> ..
> 
> Mmmm...  I see two remaining problems with this:
> 
> -- bad sectors (media errors) will cause inappropriate speed-downs.

No.  Media error is category 0 error which doesn't affect speed down at all.

> -- deliberate (or otherwise) errors via SG_IO will cause inappropriate
> speed-downs.

No, only device errors issued via block layer are considered for speed
down (ATA_QCFLAG_IO).  SG_IO commands will never trigger speed down
unless the error is HSM or timeout.

Thanks.

-- 
tejun
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