Re: [RFC] Heads up on sys_fallocate()

[JÃrn Engel]

On Mon, 5 March 2007 00:32:14 +0000, Anton Altaparmakov wrote:
> 
> I don't know how your compression algorithm works [...]

LogFS is designed for flash media, so it does not have to worry much
about reducing disk seeks.  It is log-structured, which simplifies
compression further.

When writing a block, it basically compresses it and appends it to the
log.  Writes only have to be byte-aligned, so no space is lost for
padding.

The bad news for posix_fallocate() is that even if libc is smart enough
to write random data, mmap() can still cause problems.  If the VM
decides to write a given page twice, the second write compresses better
and the medium has filled up between the two writes, the users will have
fun.

JÃrn

-- 
Joern's library part 9:
http://www.scl.ameslab.gov/Publications/Gus/TwelveWays.html
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