Re: Short circuiting data_unlock in ext2fs

[Justus Winter]

On Wed, 12 May 2010 06:19:29 +0200
Justus Winter <4winter@informatik.uni-hamburg.de> wrote:
> And here are the results:
> 
> Benchmarking /home/teythoon/ext2fs.vanilla...
> Running 'dd if=/dev/zero of=/mnt/sink bs=1M count=51'...
> 2.28 2.27 2.28 2.30 2.30 Average: 2.286
> Running 'tar xf /tmp/ramdisk/hurd_20090404.orig.tar.gz -C /mnt'...
> 23.23 23.15 23.26 23.02 23.13 Average: 23.158
> Benchmarking /home/teythoon/ext2fs.sc_unlock...
> Running 'dd if=/dev/zero of=/mnt/sink bs=1M count=51'...
> 2.32 2.06 2.33 2.09 2.36 Average: 2.232
> Running 'tar xf /tmp/ramdisk/hurd_20090404.orig.tar.gz -C /mnt'...
> 23.00 23.15 23.08 22.84 22.73 Average: 22.96
> 
> If there's anything wrong with my benchmarking method or if you want
> me to increase the amount of data written or the number of runs,
> please let me know.

Since the performance of my hard drive is of little interest here, I
ran the script again, once with the call to sync removed and once with
a storeio based ramdisk as backend:

Benchmarking /home/teythoon/ext2fs.vanilla...
Running 'dd if=/dev/zero of=/mnt/sink bs=1M count=51'...
2.05 2.29 2.07 2.25 2.19 Average: 2.17
Running 'tar xf /tmp/ramdisk/hurd_20090404.orig.tar.gz -C /mnt'...
24.08 23.22 22.94 23.56 22.89 Average: 23.338
Benchmarking /home/teythoon/ext2fs.sc_unlock...
Running 'dd if=/dev/zero of=/mnt/sink bs=1M count=51'...
2.32 2.00 2.40 2.05 2.30 Average: 2.214
Running 'tar xf /tmp/ramdisk/hurd_20090404.orig.tar.gz -C /mnt'...
22.74 22.94 23.26 23.41 23.06 Average: 23.082

Benchmarking /home/teythoon/ext2fs.vanilla.static...
Running 'dd if=/dev/zero of=/mnt/sink bs=1M count=51'...
2.60 2.48 2.56 2.52 2.55 Average: 2.542
Running 'tar xf /tmp/ramdisk/hurd_20090404.orig.tar.gz -C /mnt'...
18.70 18.70 18.67 18.78 18.75 Average: 18.72
Benchmarking /home/teythoon/ext2fs.sc_unlock.static...
Running 'dd if=/dev/zero of=/mnt/sink bs=1M count=51'...
2.30 2.35 2.30 2.30 2.30 Average: 2.31
Running 'tar xf /tmp/ramdisk/hurd_20090404.orig.tar.gz -C /mnt'...
18.73 18.74 18.78 18.75 18.80 Average: 18.76

Somehow I expected the performance of the storeio backed filesystem to
be somewhat better...

Justus

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