Messages in this thread | | | Date | Fri, 27 Mar 2009 20:14:04 -0400 | From | Jeff Garzik <> | Subject | Re: [PATCH 0/3] Ext3 latency improvement patches |
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Theodore Tso wrote: > OTOH, the really big databases will tend to use direct I/O, so they > won't be dirtying the page cache anyway. So maybe it's not worth the
Not necessarily... From what I understand, a lot of the individual low-level components in cloud storage, such as GoogleFS's chunk server[1] do not bypass the page cache, even though they do care about the details of data caching and data consistency.
I am looking at the same areas for my own distributed storage work, and am finding that the current crop of Linux-specific, database/server-friendly syscalls permit more application control over pagecache usage than in past years, decreasing the need for O_DIRECT. Things like readahead(2), sync_file_range(2), fadvise(3), really help.
Jeff
[1] http://labs.google.com/papers/gfs-sosp2003.pdf
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