linux-kernel - Re: [PATCH] ide-cd: remove the internal 64k buffer

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Message-Id: <200802192251.37183.bzolnier@gmail.com>
Date:	Tue, 19 Feb 2008 22:51:36 +0100
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	petkovbb@...il.com
Cc:	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org
Subject: Re: [PATCH] ide-cd: remove the internal 64k buffer


Hi,

On Tuesday 19 February 2008, Borislav Petkov wrote:
> Hi Bart,
> 
> here's one more item from my TODO list. The removal is straight forward, after
> testing it with all my cdrom drives they all seem even to rotate quieter due to
> the automatic speed adjustment of the drive to the continuous data stream
> bandwidth in contrast to the buffer-mode in which recurring buffer-fill speedups
> caused the drive's read speeed to spike in order to keep the buffer filled up
> constantly.
> 
> Still, i'd keep this a bit longer in -mm to see whether there are some
> other issues with it and with all the different workloads.
> 
> 
> commit a855bd5d94ddac678cf90b4b8f20dbd3ac8ea29a
> Author: Borislav Petkov <petkovbb@...il.com>
> Date:   Tue Feb 19 14:25:09 2008 +0100
> 
>     ide-cd: remove the internal 64k buffer
>     
>     This removes the internal ide-cd buffer and falls back to read-ahead block layer
>     capabilities. Thorough testing (cd burning, dvd read, raw read) gives with the
>     bufferless mode marginally better performance in addition to simplified code.
>     
>     bufferless:
>     
>     dd: reading `/dev/hdc': Input/output error
>     6238+0 records in
>     6238+0 records out
>     204406784 bytes (204 MB) copied, 259.891 s, 787 kB/s
>     
>     real    4m21.598s
>     user    0m0.014s
>     sys     0m0.744s
>     
>     with the old buffer (2.6.25-rc1):
>     
>     dd: reading `/dev/hdc': Input/output error
>     6238+0 records in
>     6238+0 records out
>     204406784 bytes (204 MB) copied, 262.893 s, 778 kB/s
>     
>     real    4m22.938s
>     user    0m0.009s
>     sys     0m0.771s
>     
>     Signed-off-by: Borislav Petkov <petkovbb@...il.com>

applied, thanks
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