Messages in this thread |  | | Date | Mon, 14 Jan 2013 11:14:23 +0800 | From | Aaron Lu <> | Subject | Re: [PATCH v6 0/4] block layer runtime pm |
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On Tue, Jan 08, 2013 at 10:27:54AM -0500, Alan Stern wrote: > On Tue, 8 Jan 2013, Aaron Lu wrote: > > > So this also reminds me that as long as CONFIG_PM_RUNTIME is selected, > > the blk_pm_add/put/peek_request functions will be in the block IO path. > > Shall we introduce a new config option to selectively build block > > runtime PM functionality? something like CONFIG_BLK_PM_RUNTIME perhaps? > > > > Just some condition checks in those functions, not sure if it is worth a > > new config though. Please suggest, thanks. > > I don't think it is needed. The new routines will be very quick when > blk_pm_runtime_init() hasn't been called, once you add back the checks > for the queue's device.
Is it necessary to also add the q->dev check in the following case?
static void blk_pm_requeue_request(struct request *rq) { if (rq->q->dev && !(rq->cmd_flags & REQ_PM)) rq->q->nr_pending--; }
So that we do not have a meanlingless value of nr_pending for those drivers that don't use block runtime PM, and this also has the benefit of making those drivers return early.
Thanks, Aaron
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