Re: The difference of request dir between AS and Deadline I/O scheduler?

Jens Axboe
2009-03-02T12:25:58Z

On Mon, Mar 02 2009, ???? wrote:
> Hi,
>
> I'm little confused about the defination of request dir in AS and
> Deadline I/O scheduler.
> In AS, the request dir is defined by wheher it's sync:
>
> data_dir = rq_is_sync(rq);
>
> But in Deadline, the requests are grouped by read and write.
>
> Why is there the difference since AS is an extension of Deadline?
> what's the consideration?

Because AS uses the sync vs async distinction to decide whether to
anticipate a new request from that process. 'sync' is then reads or sync
writes, whereas deadline does not distinguish between sync and async
writes.

--
Jens Axboe