Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 5 Jun 2003 14:18:40 +0200 | From | Rogier Wolff <> | Subject | Fwd: Fwd: VFAT performance. |
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Hi,
For the performance freaks: We're copying some data off a VFAT32 partition. We've opened the drive. (Yes I know, you're not supposed to do that. "Don't do this at home folks!" :-)
When copying /dev/hda, we were able to achieve 11Mbyte per second: Our 100mpbs ethernet throughput.
When copying large files off /mnt, we see a performance of about 7Mb per second. We see the head seek to the FAT about twice per second. This fits in with:
4K bytes of FAT contains 1024 fat entries. with a 4K clustersize, that would describe about 4Mbytes worth of data. So, at 7Mbytes per second we require a new FAT block twice per second.
I think that we're loosing the 4Mbytes per second of performance due to the 4 seeks per second that the drive has to perform.
The way to fix this would be to be able to assign a higher cache priority (*) to the blocks in the FAT, and to read more than just 4k per seek to the FAT.
Just something to keep in mind when fiddling with the code again....
Roger.
(*) i.e. expire them from the buffer cache less easily than normal blocks.
-- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 ** *-- BitWizard writes Linux device drivers for any device you may have! --* * The Worlds Ecosystem is a stable system. Stable systems may experience * * excursions from the stable situation. We are currently in such an * * excursion: The stable situation does not include humans. *************** - 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/
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