[PATCHSET] blk-throttle: implement proper hierarchy support

[Vivek Goyal]

On Wed, May 01, 2013 at 05:39:18PM -0700, Tejun Heo wrote:

[..]
> While this patchset contains many patches, the implementation is
> pretty straight-forward.  throtl_grp's form a tree anchored at
> throtl_data and bios climb the tree as they get dispatched at each
> level.  The bios which reach the top of the tree - throl_data - are
> issued. 

Have a question here. Looks like when bio climbs from child group
to parent group, then parent group slice starts fresh if parent
was empty. So if we have a parent with 1MB/s limit and a child with
1MB/s limit and a bio gets queued in child, then looks like effective
IO rate would be .5MB/s and not 1MB/s?

IOW, when child gets queued, we should start time accounting for
all parents in the hiearchy too.

Thanks
Vivek