Messages in this thread | | | From | Greg Thelen <> | Date | Thu, 22 Jul 2010 12:28:50 -0700 | Subject | Re: [RFC][PATCH 00/11] blkiocg async support |
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On Sun, Jul 11, 2010 at 5:20 PM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > On Sat, 10 Jul 2010 09:24:17 -0400 > Vivek Goyal <vgoyal@redhat.com> wrote: > >> On Fri, Jul 09, 2010 at 05:55:23PM -0700, Nauman Rafique wrote: >> >> [..] >> > > Well, right. I agree. >> > > But I think we can work parallel. I will try to struggle on both. >> > >> > IMHO, we have a classic chicken and egg problem here. We should try to >> > merge pieces as they become available. If we get to agree on patches >> > that do async IO tracking for IO controller, we should go ahead with >> > them instead of trying to wait for per cgroup dirty ratios. >> > >> > In terms of getting numbers, we have been using patches that add per >> > cpuset dirty ratios on top of NUMA_EMU, and we get good >> > differentiation between buffered writes as well as buffered writes vs. >> > reads. >> > >> > It is really obvious that as long as flusher threads ,etc are not >> > cgroup aware, differentiation for buffered writes would not be perfect >> > in all cases, but this is a step in the right direction and we should >> > go for it. >> >> Working parallel on two separate pieces is fine. But pushing second piece >> in first does not make much sense to me because second piece does not work >> if first piece is not in. There is no way to test it. What's the point of >> pushing a code in kernel which only compiles but does not achieve intented >> purposes because some other pieces are missing. >> >> Per cgroup dirty ratio is a little hard problem and few attempts have >> already been made at it. IMHO, we need to first work on that piece and >> get it inside the kernel and then work on IO tracking patches. Lets >> fix the hard problem first that is necessary to make second set of patches >> work. >> > > I've just waited for dirty-ratio patches because I know someone is working on. > But, hmm, I'll consider to start work by myself.
I have some patches that I have to address the dirty-ratios. I will post them.
These dirty-ratio patches do not do anything intelligent wrt to per-cgroup writeback. When a cgroup dirty ratio is exceeded, a per-bdi writeback is triggered.
> (Off-topic) > BTW, why io-cgroup's hierarchy level is limited to 2 ? > Because of that limitation, libvirt can't work well... > > Thanks, > -Kame > > -- > 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/ > -- 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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