Re: [PATCH v5 3/4] block: implement runtime pm strategy

From: Matthew Wilcox
Date: Fri Jul 06 2012 - 03:35:49 EST

On Fri, Jul 06, 2012 at 12:04:31PM +0800, Lin Ming wrote:
> When a request is added:
> If device is suspended or is suspending and the request is not a
> PM request, resume the device.
> When a request finishes:
> Call pm_runtime_mark_last_busy().
> When pick a request:
> If device is resuming/suspending, then only PM request is allowed to go.
> Return NULL for other cases.

This only works for drivers which are struct request based. For those
that handle struct bio directly, nr_pending will always be 0.

I think the right place to increment nr_pending is in generic_make_request.
But I'm not sure where to decrement it. I think we need a blk_bio_endio()
which does some housekeeping and then calls bio_endio().

Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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