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 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
