On Thu, Aug 17 2017, Bart Van Assche wrote: > It is nontrivial to derive from the blk-mq source code when > blk_mq_tags.active_queues is decremented. Hence add a comment that > explains this. > > Signed-off-by: Bart Van Assche <[email protected]> > Cc: Christoph Hellwig <[email protected]> > Cc: Hannes Reinecke <[email protected]> > Cc: Johannes Thumshirn <[email protected]> > --- > block/blk-mq.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index f84d145490bf..b86d2cafc355 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -834,6 +834,10 @@ static void blk_mq_timeout_work(struct work_struct *work) > } else { > struct blk_mq_hw_ctx *hctx; > > + /* > + * All requests finished (latest request timeout) seconds ago, > + * so mark each hctx as idle. > + */ > queue_for_each_hw_ctx(q, hctx, i) {
I don't think that's a great comment, what does 'latest request timeout' refer to? We hit this case when the device has gone idle, I think a more useful comment would be something about how blk-mq implements timeouts. How about something ala: /* * Request timeouts are handled as a forward rolling timer. If we * end up here, there are no more requests pending, and there hasn't * been for a while. Mark each hctx as idle. */ -- Jens Axboe
