Messages in this thread | | | Date | Mon, 23 Jan 2012 11:33:35 -0800 | From | Tejun Heo <> | Subject | Re: [PATCH 08/17] blkcg: shoot down blkio_groups on elevator switch |
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On Mon, Jan 23, 2012 at 10:43:36AM -0800, Tejun Heo wrote: > Yeah, this is much more arguable. I don't think it would be too > complex to keep per-policy granularity even w/ unified blkg managed by > blkcg core (we'll just need to point to separately allocated > per-policy data from the unified blkg and clear them selectively). > I'm just not convinced of its necessity. With initial config out of > the way, elvs and blkcg policies don't get molested all that often. > > I'll see how complex it actually gets. If it isn't too much > complexity, yeah, why not...
Hmmm... while this isn't terribly complex, it involves considerable amount of churn as core layer doesn't currently know what policies are bound to which queues how - we'll have to add some part of that before shootdown change, use it there, and then later replace it with proper per-queue thing. The conversion is already painful enough without adding another chunk to juggle around. Given that clearing all on pol change isn't too crazy, how about the following?
* For now, clear unconditionally on pol/elv change.
* But structure things such that policy specific data are allocated separately and on pol/elv change only those policy specific part is flushed.
* Later, if deemed necessary, make the clearing of pol-specific part selective.
-- tejun
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