Messages in this thread | | | Subject | Re: fsync on large files | From | Andi Kleen <> | Date | 14 Feb 1999 09:29:06 +0100 |
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In article <199902140429.XAA29350@dcl>, tytso@MIT.EDU (Theodore Y. Ts'o) writes:
> What the patch does is keep an array of the last four blocks which were > modified since the last fsync(). If there have been no more than four > blocks modified, then the ext2 filesystem can do a "fast fsync", which > just flushes those four (or fewer) blocks to disk, without having to > walk all of the indirect blocks looking for modified blocks. This > should be extremely effective for programs like syslog which are doing > frequent fsync()'s with minimal amounts of data written between calls to > fsync().
This is a very important patch, because fsync() is needed in some transaction oriented databases (they have to call fsync() or fdatasync() on the log frequently to commit operations). For some of them 4 blocks could be not enough though, perhaps a more generic version of your patch that handles more than 4 blocks could be found - like keeping the dirty blocks per inode on a special list.
-Andi
-- This is like TV. I don't like TV.
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