On Mon 21-01-13 18:11:30, Ted Tso wrote: > On Tue, Jan 22, 2013 at 12:04:32AM +0100, Sedat Dilek wrote: > > > > Beyond the FUSE/LOOP fun, will you apply this patch to your linux-next GIT tree? > > > > Feel free to add... > > > > Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> > > > > A similiar patch for JBD went through your tree into mainline (see [1] and [2]). > > I'm not at all convinced that this patch has anything to do with your > problem. I don't see how it could affect things, and I believe you > mentioned that you saw the problem even with this patch applied? (I'm > not sure; some of your messages which you sent were hard to > understand, and you mentioned something about trying to send messages > when low on sleep :-). > > In any case, the reason why I haven't pulled this patch into the ext4 > tree is because I was waiting for Eric and some of the performance > team folks at Red Hat to supply some additional information about why > this commit was making a difference in performance for a particular > proprietary, closed source benchmark. Just a small correction - it was aim7 AFAIK which isn't closed source (anymore). You can download it from SourceForge (http://sourceforge.net/projects/aimbench/files/aim-suite7/Initial%20release/). Now I have some reservations about what the benchmark does but historically it has found quite a few issues for us as well. > I'm very suspicious about applying patches under the "cargo cult" > school of programming. ("We don't understand why it makes a > difference, but it seems to be good, so bombs away!" :-) Well, neither am I ;) But it is obvious the patch speeds up log_start_commit() by 'a bit' (taking spinlock, disabling irqs, ...). And apparently 'a bit' is noticeable for particular workload on a particular machine - commit statistics Eric provided showed that clearly. I'd still be happier if Eric also told us how much log_start_commit() calls there were so that one could verify that 'a bit' could indeed multiply to a measurable difference. But given how simple the patch is, I gave away after a while and just merged it... Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
