Messages in this thread | | | Date | Mon, 5 Mar 2007 12:49:45 +0100 | From | Jörn Engel <> | Subject | Re: [RFC] Heads up on sys_fallocate() |
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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.
Jörn
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