Messages in this thread |  | | Date | Wed, 2 Jan 2013 11:52:42 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH 23/24] cfq-iosched: collect stats from dead cfqgs |
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Hey, Vivek.
On Wed, Jan 02, 2013 at 11:44:15AM -0500, Vivek Goyal wrote: > > > In fact if we have a realiable way of resetting status then online/offline > > > infrastructure might not be required? I think per cpu stats will be a > > > problem though and that's why we probably require logic to online/offline > > > the group? > > > > Hmmm? What do you mean? > > I mean if we had a reliable way of resetting stats after transferring > then we would not need to keep a track of whether group is online/offline. > We could add everything and adding zero will not change anything. In fact > it will also take care of residual IO (IO which happened after transfer > of stats).
Ah... yeah, if we can do atomic transfer, we might be able to do away with on/offlining. Couldn't think of a way to do that without incurring overhead to hot paths.
> Or I missed the real reason of why do we have group online/offline > infrastructure.
But given that on/offline state is something common to cgroup, I don't think adding the states to blkcg is a bad idea. We need it for reliable iterations anyways.
Thanks.
-- tejun
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