Re: [RFC, PATCH] cfq-iosched: remove redundant queuing detection code

[Jeff Moyer <jmoyer@redhat.com>]

Jens Axboe <jens.axboe@oracle.com> writes:

>> Why don't we simply use the value configured via the queue_depth sysfs
>> file?
>
> First of all, that only covers SCSI. We could do that by having the tag
> on/off functions set the same flag. But even for such devices, actual
> tag depth is dependent upon what other devices are on the controller
> (since it's often a shared map) and may not even be statically
> detectable in the sense that actual depth is only really seen when the
> device returns busy on a queue attempt.
>
> In most cases it would work fine, but the dynamic detection is more
> reliable. The sysfs setting in reality is max setting.

OK, thanks for the patient explanation, Jens!

Cheers,
Jeff