On Tue 22-01-13 19:37:46, Eric Sandeen wrote: > On 1/22/13 5:50 PM, Jan Kara wrote: > > 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... > > I am still trying to get our perf guys to collect that data, FWIW... > I will send it when I get it. I bugged them again today. :) > > (Just to be sure: I was going to measure the wakeups the old way, and the > avoided wakeups with the new change; sound ok?) Yes, that would be what I'm interested in. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- 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
