On Sat 26-01-08 08:27:43, Al Boldi wrote: > Diego Calleja wrote: > > El Thu, 24 Jan 2008 23:36:00 +0300, Al Boldi <a1426z@xxxxxxxxx> escribió: > > > Greetings! > > > > > > data=ordered mode has proven reliable over the years, and it does this > > > by ordering filedata flushes before metadata flushes. But this > > > sometimes causes contention in the order of a 10x slowdown for certain > > > apps, either due to the misuse of fsync or due to inherent behaviour > > > like db's, as well as inherent starvation issues exposed by the > > > data=ordered mode. > > > > There's a related bug in bugzilla: > > http://bugzilla.kernel.org/show_bug.cgi?id=9546 > > > > The diagnostic from Jan Kara is different though, but I think it may be > > the same problem... > > > > "One process does data-intensive load. Thus in the ordered mode the > > transaction is tiny but has tons of data buffers attached. If commit > > happens, it takes a long time to sync all the data before the commit > > can proceed... In the writeback mode, we don't wait for data buffers, in > > the journal mode amount of data to be written is really limited by the > > maximum size of a transaction and so we write by much smaller chunks > > and better latency is thus ensured." > > > > > > I'm hitting this bug too...it's surprising that there's not many people > > reporting more bugs about this, because it's really annoying. > > > > > > There's a patch by Jan Kara (that I'm including here because bugzilla > > didn't include it and took me a while to find it) which I don't know if > > it's supposed to fix the problem , but it'd be interesting to try: > > Thanks a lot, but it doesn't fix it. Hmm, if you're willing to test patches, then you could try a debug patch: http://bugzilla.kernel.org/attachment.cgi?id=14574 and send me the output. What kind of load do you observe problems with and which problems exactly? Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
