| Message ID | 20190828022947.23364-5-damien.lemoal@wdc.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Elevator cleanups and improvements | expand |
On Wed, Aug 28, 2019 at 11:29:44AM +0900, Damien Le Moal wrote: > For block devices that do not specify required features, preserve the > current default elevator selection (mq-deadline for single queue > devices, none for multi-queue devices). However, for devices specifying > required features (e.g. zoned block devices ELEVATOR_F_ZBD_SEQ_WRITE > feature), select the first available elevator providing the required > features. > > In all cases, default to "none" if no elevator is available or if the > initialization of the default elevator fails. > > Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Looks good, Reviewed-by: Christoph Hellwig <hch@lst.de>
On Tue, 2019-09-03 at 01:57 -0700, Christoph Hellwig wrote: > On Wed, Aug 28, 2019 at 11:29:44AM +0900, Damien Le Moal wrote: > > For block devices that do not specify required features, preserve the > > current default elevator selection (mq-deadline for single queue > > devices, none for multi-queue devices). However, for devices specifying > > required features (e.g. zoned block devices ELEVATOR_F_ZBD_SEQ_WRITE > > feature), select the first available elevator providing the required > > features. > > > > In all cases, default to "none" if no elevator is available or if the > > initialization of the default elevator fails. > > > > Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> > > Looks good, > > Reviewed-by: Christoph Hellwig <hch@lst.de> Thanks, but I need to fix this patch too. The "if (q->nr_hw_queues != 1)" at the beginning of elevator_init_mq() must be removed. I am sending a v3 with this fix and a modified patch 5 to call elevator_init_mq() earlier in device_add_disk().
diff --git a/block/elevator.c b/block/elevator.c index 2235dfe6755b..81d0877dbc34 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -665,9 +665,46 @@ static inline bool elv_support_iosched(struct request_queue *q) } /* - * For blk-mq devices supporting IO scheduling, we default to using mq-deadline, - * if available, for single queue devices. If deadline isn't available OR - * deadline initialization fails OR we have multiple queues, default to "none". + * For single queue devices, default to using mq-deadline. If we have multiple + * queues or mq-deadline is not available, default to "none". + */ +static struct elevator_type *elevator_get_default(struct request_queue *q) +{ + if (q->nr_hw_queues != 1) + return NULL; + + return elevator_get(q, "mq-deadline", false); +} + +/* + * Get the first elevator providing the features required by the request queue. + * Default to "none" if no matching elevator is found. + */ +static struct elevator_type *elevator_get_by_features(struct request_queue *q) +{ + struct elevator_type *e; + + spin_lock(&elv_list_lock); + + list_for_each_entry(e, &elv_list, list) { + if (elv_support_features(e->elevator_features, + q->required_elevator_features)) + break; + } + + if (e && !try_module_get(e->elevator_owner)) + e = NULL; + + spin_unlock(&elv_list_lock); + + return e; +} + +/* + * For a device queue that has no required features, use the default elevator + * settings. Otherwise, use the first elevator available matching the required + * features. If no suitable elevator is find or if the chosen elevator + * initialization fails, fall back to the "none" elevator (no elevator). */ void elevator_init_mq(struct request_queue *q) { @@ -685,7 +722,10 @@ void elevator_init_mq(struct request_queue *q) if (unlikely(q->elevator)) return; - e = elevator_get(q, "mq-deadline", false); + if (!q->required_elevator_features) + e = elevator_get_default(q); + else + e = elevator_get_by_features(q); if (!e) return;
For block devices that do not specify required features, preserve the current default elevator selection (mq-deadline for single queue devices, none for multi-queue devices). However, for devices specifying required features (e.g. zoned block devices ELEVATOR_F_ZBD_SEQ_WRITE feature), select the first available elevator providing the required features. In all cases, default to "none" if no elevator is available or if the initialization of the default elevator fails. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- block/elevator.c | 48 ++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 44 insertions(+), 4 deletions(-)