On Sat, 25 May 2019 at 05:48, Tejun Heo <tj@xxxxxxxxxx> wrote:
>
> On Thu, May 23, 2019 at 06:44:12AM +0000, xxhdx1985126@xxxxxxxxx wrote:
> > From: Xuehan Xu <xuxuehan@xxxxxx>
> >
> > this controller is supposed to facilitate limiting
> > the metadata ops or data ops issued to the underlying
> > cluster.
>
> Replied on the other post but I'm having a hard time seeing why this
> is necessary. Please explain in detail.
Hi, Tejun, thanks for your review:)
The reason that we implemented a ceph-specific controller is as follows:
We have a need to limit our docker instances' rate of io issued
to the underlying Cephfs cluster. As the limitation has to be in the
granularity of docker instance, we think maybe we can leverage the
cgroup interface. At the time, we thought no existing cgroup
controller can satisfy our requirement, as we thought the blkio
controller, the only io related controller, is dedicated to restrain
the io issued to block devices. So we implemented a new controller.
However, Ilya Dryomov pointed out, in another thread in the mailing
list ceph-devel, that the blkio controller is supposed to handle any
io now. We now think maybe we should try to leverage the blkio
controller to implement the cephfs io limiting mechanism. Am I right
about this? Thanks:-)
>
> Thanks.
>
> --
> tejun
