[Bug 14914] files are created as sparse files when they shouldn't

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=14914





--- Comment #40 from Alex Y. Shalimov <ashalimov at gmail.com>  2010-07-07 08:55:42 ---
Tested the same program on Linux. The results are quite predictable:

filetest2
(write-last-byte preallocation, random write) 131056 fragments. Run time 36
sec.

filetest2 -posix-prealloc
(preallocation via posix_falloc, random write) 611 fragments (good). But run
time was 6 min 52 sec! And preallocation didn't take much time; most of it was
lost during write. I've tried to preallocate by first filling file sequentially
and then performing random write, but run time was nearly identical (6 min 29
sec), as well as fragments number (617). For some reason it takes too long to
overwrite already written data.

filetest2 -write-only -sequential-write
(no preallocation, sequential write) 660 fragments, only 10 sec.

filetest2 -write-only
(no preallocation, random write) 131069 fragments, 36 seconds. Linux is very
predictable :-)

So, basically this version behaves like the previous one. Unfortunately, any
attempts to preallocate space leads to insanely decreased write speed. Probably
we'll have to deal with heavily fragmented files, unless someone knows any
other way to preallocate file space. Or maybe ext3 is just plane bad, and we
should move to something more advanced (there are enough alternatives). Thanks
for reading!

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