Messages in this thread | | | Subject | Re: [PATCH 16/16] blkio: Documentation | From | "Alan D. Brunelle" <> | Date | Tue, 17 Nov 2009 13:07:59 -0500 |
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On Fri, 2009-11-13 at 12:40 -0500, Vivek Goyal wrote: > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> > --- > Documentation/cgroups/blkio-controller.txt | 100 ++++++++++++++++++++++++++++ > 1 files changed, 100 insertions(+), 0 deletions(-) > create mode 100644 Documentation/cgroups/blkio-controller.txt > > diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt > new file mode 100644 > index 0000000..6fb772f > --- /dev/null > +++ b/Documentation/cgroups/blkio-controller.txt > @@ -0,0 +1,100 @@ > + Block IO Controller > + =================== > +Overview > +======== > +cgroup subsys "blkio" implements the block io controller. There seems to be > +a need of various kind of IO control policies (like proportional BW, max BW)
Change to: "a need for various kinds"
> +both at leaf nodes as well as at intermediate nodes in storage hierarchy. Plan
Change to: "in a storage hierarchy"
> +is to use same cgroup based management interface for blkio controller and
Change to: "use the same cgroup"
> +based on user options switch IO policies in the background. > + > +In the first phase, this patchset implements proportional weight time based > +division of disk policy. It is implemented in CFQ. Hence this policy takes > +effect only on leaf nodes when CFQ is being used. > + > +HOWTO > +===== > +You can do a very simple testing of running two dd threads in two different > +cgroups. Here is what you can do. > + > +- Enable group scheduling in CFQ > + CONFIG_CFQ_GROUP_IOSCHED=y > + > +- Compile and boot into kernel and mount IO controller (blkio). > + > + mount -t cgroup -o blkio none /cgroup > + > +- Create two cgroups > + mkdir -p /cgroup/test1/ /cgroup/test2 > + > +- Set weights of group test1 and test2 > + echo 1000 > /cgroup/test1/blkio.weight > + echo 500 > /cgroup/test2/blkio.weight > + > +- Create two same size files (say 512MB each) on same disk (file1, file2) and > + launch two dd threads in different cgroup to read those files. > + > + sync > + echo 3 > /proc/sys/vm/drop_caches > + > + dd if=/mnt/sdb/zerofile1 of=/dev/null & > + echo $! > /cgroup/test1/tasks > + cat /cgroup/test1/tasks > + > + dd if=/mnt/sdb/zerofile2 of=/dev/null & > + echo $! > /cgroup/test2/tasks > + cat /cgroup/test2/tasks > + > +- At macro level, first dd should finish first. To get more precise data, keep > + on looking at (with the help of script), at blkio.disk_time and
Change to: "on looking at blkio.disk_time and"
> + blkio.disk_sectors files of both test1 and test2 groups. This will tell how > + much disk time (in milli seconds), each group got and how many secotors each
Change to: "much disk time (in milliseconds) each group got and how many sectors each"
> + group dispatched to the disk. We provide fairness in terms of disk time, so > + ideally io.disk_time of cgroups should be in proportion to the weight.
Change to: "ideally the io.disk_time of each cgroup should be in proportion to its weight."
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