On Tue, Aug 29, 2000 at 06:08:14PM -0700, Linus Torvalds wrote:
>
>
> On Wed, 30 Aug 2000, Jens Axboe wrote:
> >
> > Maybe I wasn't very clear... What I mean is that drivers that use
> > blk_queue_make_request (such as md) are handed buffers directly and
> > don't get requests added to their queues in the regular sense, instead
> > they remap b_rdev before ll_rw_blk gets the queue for the device and
> > adds them to the destination queue.
>
> Ho humm.. I actually kind of expected the statistics to be done in
> generic_make_request(), so that we'd have
>
> .....
> do {
> q = blk_get_queue(bh->b_rdev);
> if (!q) {
> ... no such device ..
> }
> + statistics(q, rw, bh->b_size);
> } while (q->make_request_fn(q, rw, bh)));
> ...
>
> and just remove the drive_stat_acct() thing completely.
>
> That way, we'd have a per-queue "this many reads, this many writes".
Does this setup also allow to maintain time statistics, like the times between
make_request_time, io_start_time and io_end_time so things like queuetime
and io servicetime can be determined?
-Marcel
--
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