lkml.org 
[lkml]   [2012]   [Apr]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/6] buffered write IO controller in balance_dirty_pages()
On Sun, Apr 01, 2012 at 09:46:06AM +0530, Suresh Jayaraman wrote:
> On 03/28/2012 05:43 PM, Fengguang Wu wrote:
> > Here is one possible solution to "buffered write IO controller", based on Linux
> > v3.3
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux.git buffered-write-io-controller
> >
>
> The implementation looks unbelievably simple. I ran a few tests
> (throttling) and I found it working well generally.

Thanks for test it out :)

> > Features:
> > - support blkio.weight
> > - support blkio.throttle.buffered_write_bps
> >
> > Possibilities:
> > - it's trivial to support per-bdi .weight or .buffered_write_bps
> >
> > Pros:
> > 1) simple
> > 2) virtually no space/time overheads
> > 3) independent of the block layer and IO schedulers, hence
> > 3.1) supports all filesystems/storages, eg. NFS/pNFS, CIFS, sshfs, ...
> > 3.2) supports all IO schedulers. One may use noop for SSDs, inside virtual machines, over iSCSI, etc.
> >
> > Cons:
> > 1) don't try to smooth bursty IO submission in the flusher thread (*)
> > 2) don't support IOPS based throttling
> > 3) introduces semantic differences to blkio.weight, which will be
> > - working by "bandwidth" for buffered writes
> > - working by "device time" for direct IO
>
> There is a chance that this semantic difference might confuse users.

Yeah.

> > (*) Maybe not a big concern, since the bursties are limited to 500ms: if one dd
> > is throttled to 50% disk bandwidth, the flusher thread will be waking up on
> > every 1 second, keep the disk busy for 500ms and then go idle for 500ms; if
> > throttled to 10% disk bandwidth, the flusher thread will wake up on every 5s,
> > keep busy for 500ms and stay idle for 4.5s.
> >
> > The test results included in the last patch look pretty good in despite of the
> > simple implementation.
> >
> > [PATCH 1/6] blk-cgroup: move blk-cgroup.h in include/linux/blk-cgroup.h
> > [PATCH 2/6] blk-cgroup: account dirtied pages
> > [PATCH 3/6] blk-cgroup: buffered write IO controller - bandwidth weight
> > [PATCH 4/6] blk-cgroup: buffered write IO controller - bandwidth limit
> > [PATCH 5/6] blk-cgroup: buffered write IO controller - bandwidth limit interface
> > [PATCH 6/6] blk-cgroup: buffered write IO controller - debug trace
> >
>
> How about a BOF on this topic during LSF/MM as there seems to be enough
> interest?

Sure. I'll talk briefly about the block IO cgroup in the writeback
session. I'm open to more oriented technical discussions in some later
time if necessary.

Thanks,
Fengguang


\
 
 \ /
  Last update: 2012-04-01 18:55    [W:0.082 / U:4.468 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site