[Ubuntu-zh] [ANNOUNCE] bfq disk I/O scheduler

Aron Xu happyaron.xu在gmail.com
星期一 八月 9 05:34:14 BST 2010


2010/8/9 Aron Xu <happyaron.xu在gmail.com>:
> 这是传说中的 BFS 吧?
> ---------- Forwarded message ----------
> From: Paolo Valente <posta_paolo在yahoo.it>
> Date: Wed, Aug 4, 2010 at 17:52
> Subject: [ANNOUNCE] bfq disk I/O scheduler
> To: ubuntu-devel在lists.ubuntu.com
> Hi,
> I have been working for a few years (with Fabio Checconi) on a disk
> scheduler providing definitely lower latencies than cfq, as well as a
> higher throughput with most of the test workloads we used (or the same
> throughput as cfq with the other workloads). We named this scheduler
> bfq (budget fair queueing). I hope this is the right list for announcing
> this work.
> One of the things we measured in our tests is the cold-cache execution
> time of a command as, e.g., "bash -c exit", "xterm /bin/true" or
> "konsole -e /bin/true", while the disk was also accessed by different
> combinations of sequential, or random, readers and/or
> writers. Depending on which of these background workloads was used,
> these execution times were five to nine times lower with bfq under
> 2.6.32. Under 2.6.35 they were instead from six to fourteen times
> lower. The highest price paid for these lower latencies was a 20% loss
> of aggregated disk throughput for konsole in case of background
> workloads made only of sequential requests (due to the fact that bfq
> of course privileges, more than cfq, the seeky IO needed to load
> konsole and its dependencies). In contrast, with shorter commands, as
> bash or xterm, bfq also provided up to 30% higher aggregated
> throughput.
> We saw from 15% to 30% higher aggregated throughput also in our
> only-aggregated-throughput tests. You can find in [1] all the details
> on our tests and on other nice features of bfq, such as the fact that
> it perfectly distributes the disk throughput as desired, independently
> of disk physical parameters like, e.g., ZBR. in [1] you can also find
> a detailed description of bfq and a short report on the maturity level
> of the code (TODO list), plus all the scripts used for the tests.
> The results I mentioned so far have been achieved with the last
> version of bfq, released about two months ago as patchsets for 2.6.33
> or 2.6.34. From a few days a patchset for 2.6.35 is available too, as
> well as a backport to 2.6.32. The latter has been prepared by Mauro
> Andreolini, who also helped me a lot with debugging. All these patches
> can be found here [2]. Mauro also built a binary kernel package for
> current lucid, and hosted it into a PPA, which can be found here [3].
> A few days after being released, this version of bfq has been
> introduced as the default disk scheduler in the Zen Kernel. It has
> been adopted as the default disk scheduler in Gentoo Linux too. We
> also recorded downloads from users with other distributions, including
> ArchLinux and Ubuntu itself. As of now we received only positive
> feedbacks.
> Paolo
> [1] http://algo.ing.unimo.it/people/paolo/disk_sched/
> [2] http://algo.ing.unimo.it/people/paolo/disk_sched/sources.php
> [3] Ubuntu PPA: ppa:mauro-andreolini/ubuntu-kernel-bfq
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> Regards,
> Aron Xu

Aron Xu

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