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Andrew Morton wrote: >"Curt" <curt@northarc.com> wrote: > >> > Or you can put 2.6 on par by setting >> > /proc/sys/vm/dirty_background_ratio to 40 and dirty_ratio to 60. >> >> Okay will do, is there a good comprehensive resource where I can read up on >> these (and presumably many other I/O related) variables? >> > >We've been relatively good about keeping the in-kernel documentation up to >date. For this stuff, see Documentation/filesystems/proc.txt and >Documentation/sysctl/vm.txt. > > >> > Longer-term, if your customers are using scsi, you should ensure that the >> > disks do not use a tag queue depth of more than 4 or 8. More than that >> and >> > the anticipatory scheduler becomes ineffective and you won't get that >> > multithreaded-read goodness. >> >> I've heard-tell of tweaking the elevator paramter to 'deadline', again could >> you point me to a resource where I can read up on this? And forgive the >> newbie-question, but is this a boot-time parameter, or a bit I can set in >> the /proc system, or both? >> > >It's boot-time only. We were working on making it per-disk but that was >quite complex and we really didn't get there in time. > >So add `elevator=deadline' to your kernel boot command line. From my >(brief) testing, it was a significant lose. It needs more work though: >2.6+deadline shouldn't be slower than 2.4.x > > Another thing you can do which is runtime per-disk is set /sys/block/???/queue/iosched/antic_expire to 0 which gives you something quite like deadline. >> > Please stay in touch, btw. If we cannot get applications such as yours >> > working well, we've wasted our time... >> >> I'll do what I can to provide real-world feedback, I want this to work too. >> > >Thanks. > I'd be interested in taking a look at the io scheduler if you have problems with these workloads in future. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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