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?) -Eric > Honza > -- 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
