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

From: Bartlomiej Zolnierkiewicz
Date: Tue Feb 19 2008 - 17:04:51 EST



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@xxxxxxxxx>
> 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@xxxxxxxxx>

applied, thanks
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