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From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
To: petkovbb@gmail.com
Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org
Subject: Re: [PATCH 2/4] ide-tape: remove pipeline-specific code from idetape_add_chrdev_write_request
Date: Wed, 12 Mar 2008 14:51:32 +0100	[thread overview]
Message-ID: <200803121451.33058.bzolnier@gmail.com> (raw)
In-Reply-To: <20080312054156.GC4266@gollum.tnic>

On Wednesday 12 March 2008, Borislav Petkov wrote:
> On Tue, Mar 11, 2008 at 12:25:19AM +0100, Bartlomiej Zolnierkiewicz wrote:
> > On Sunday 09 March 2008, Borislav Petkov wrote:
> > > Refrain from adding more write requests to the pipeline and queue them
> > > directly on the device's request queue instead. Prior to that flush all
> > > penging stages in the pipeline through idetape_wait_for_pipeline().
> > 
> > I would prefer to keep the original code for now
> > (it has some subtle differences).
> 
> Well, if you mean by this the while-loop below, the original code offloads
> the pipeline gradually, stage-wise, until allocation succeeds, in contrast to
> idetape_wait_for_pipeline() which iterates over all pending stages and flushes
> them all in one go.
> 
> At a certain in point in time, however, the driver might land at the unlikely
> state of still having some stages left in the pipeline while queueing all
> incoming requests on the rq queue. Therefore, i'd prefer to make sure the

This is what could happen with the unmodified driver code also.

[ thus given that pipeline code goes away completely soon there is no point
  in changing the original behavior (unless of course it is buggy and I just
  fail to see it) ]

> pipeline is empty before queueing. What is more, it is flushed only once, if
> ever, so idetape_wait_for_pipeline() simply returns in subsequent calls and no
> considerable performance penalties are imposed here.

  reply	other threads:[~2008-03-12 13:38 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-09 17:10 [PATCH 0/4] ide-tape: remove pipeline functionality-v2 Borislav Petkov
2008-03-09 17:10 ` [PATCH 1/4] ide-tape: remove tape->cache_stage Borislav Petkov
2008-03-10 23:24   ` Bartlomiej Zolnierkiewicz
2008-03-11  6:40     ` Borislav Petkov
2008-03-09 17:10 ` [PATCH 2/4] ide-tape: remove pipeline-specific code from idetape_add_chrdev_write_request Borislav Petkov
2008-03-10 23:25   ` Bartlomiej Zolnierkiewicz
2008-03-12  5:41     ` Borislav Petkov
2008-03-12 13:51       ` Bartlomiej Zolnierkiewicz [this message]
2008-03-12 14:31       ` Bartlomiej Zolnierkiewicz
2008-03-09 17:10 ` [PATCH 3/4] ide-tape remove pipeline speed/control calculations Borislav Petkov
2008-03-10 23:25   ` Bartlomiej Zolnierkiewicz
2008-03-09 17:10 ` [PATCH 4/4] ide-tape: remove pipeline-specific code from idetape_add_chrdev_read_request() Borislav Petkov
2008-03-10 23:25   ` Bartlomiej Zolnierkiewicz
2008-03-12  5:58     ` Borislav Petkov
2008-03-12 13:51       ` Bartlomiej Zolnierkiewicz
2008-03-13  6:19         ` Borislav Petkov
2008-03-10 23:24 ` [PATCH 0/4] ide-tape: remove pipeline functionality-v2 Bartlomiej Zolnierkiewicz

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