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SubjectRe: Poor floppy performance in kernel 2.4.10
On Oct 18, 2001  12:11 +0200, Kamil Iskra wrote:
> So, to reiterate, the conditions known to be necessary to reproduce it
> are: kernel >=2.4.10 (perhaps only the Linus series), small files or
> directory operations, mtools. The behaviour is as if no caching was done,
> there is a slowdown by a factor of two. I have this problem both on my
> laptop and on the desktop machine at work. They are running different
> kernel versions (2.4.12 and 2.4.10), differently configured and compiled
> by two different people. Kernel 2.4.9 and earlier worked fine.

I think this is a result of the "blockdev in pagecache" change added in
2.4.10. One of the byproducts of this change is that if a block device
is closed (no other openers) then all of the pages from this device are
dropped from the cache. In the case of a floppy drive, this is very
important, as you don't want to be cacheing data from one floppy after
you have inserted a new floppy.

In contrast, if you mounted the floppy instead of using mtools, it would
probably have good performance for small files as well.

Cheers, Andreas
--
Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert

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