On Sat, 20 Aug 2011, huang jun wrote: > hi,all > Recently,we have a test to compare async i/o and sync i/o in OSD. > The osd jounral was written in sync + direct io mode now, that heavily > infuluenced the write performance. > we use linux aio API. test file size is 40MB,and disk isn't busy. > here is the test result: > type ext3 > sync write+direct io 4.441s > > async write +direct io 0.462s > > we are glad to see that, so we want to affirm that : > 1) can we use async+direct io to achieve better write performance if > we used osd journal? Do you mean changing the writes in os/FileJournal.cc to be async? As long as the journal does not acknowledge a write until it is stable on disk, that is fine. Async IO would be a nice improvement here; I think currently it's a single sync O_DIRECT io in flight at a time. The test is to write a 40MB file via which interface? Via a kernel client mount? Thanks- sage > 2) does this bring some problems? > > thank you in advance! > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
