lkml.org 
[lkml]   [2005]   [Apr]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH scsi-misc-2.6 03/05] scsi: make scsi_queue_insert() use blk_requeue_request()
On Wed, Apr 20 2005, James Bottomley wrote:
> On Wed, 2005-04-20 at 08:15 +0900, Tejun Heo wrote:
> > - * Insert this command at the head of the queue for it's device.
> > - * It will go before all other commands that are already in the queue.
> > - *
> > - * NOTE: there is magic here about the way the queue is plugged if
> > - * we have no outstanding commands.
> > - *
> > - * Although this *doesn't* plug the queue, it does call the request
> > - * function. The SCSI request function detects the blocked condition
> > - * and plugs the queue appropriately.
>
> This comment still looks appropriate to me ... why do you want to remove
> it?
>
> > + * Requeue the command.
> > */
> > - blk_insert_request(device->request_queue, cmd->request, 1, cmd, 1);
> > + spin_lock_irqsave(q->queue_lock, flags);
> > + blk_requeue_request(q, cmd->request);
> > + spin_unlock_irqrestore(q->queue_lock, flags);
> > +
> > + scsi_run_queue(q);
>
> Really, wouldn't it be much more efficient simply to call blk_run_queue
> ()? since the blocked flags were set above, that's pretty much what
> scsi_run_queue() collapses to.

I wondered about this action recently myself. What is the point in
requeueing this request, only to call scsi_run_queue() ->
blk_run_queue() -> issue same request. If the point really is to reissue
the request immediately, I can think of many ways more efficient than
this :-)

--
Jens Axboe

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-04-21 08:16    [W:0.078 / U:1.620 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site