| Message ID | 20211119021849.2259254-5-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | blk-mq: quiesce improvement | expand |
On 11/19/21 4:18 AM, Ming Lei wrote: > Chao Leng reported that in case of lots of namespaces, it may take quite a > while for nvme_stop_queues() to quiesce all namespace queues. > > Improve nvme_stop_queues() by running quiesce in parallel, and just wait > once if global quiesce wait is allowed. > > Link: https://lore.kernel.org/linux-block/cc732195-c053-9ce4-e1a7-e7f6dcf762ac@huawei.com/ > Reported-by: Chao Leng <lengchao@huawei.com> > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- > drivers/nvme/host/core.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index 4b5de8f5435a..06741d3ed72b 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -4517,9 +4517,7 @@ static void nvme_start_ns_queue(struct nvme_ns *ns) > static void nvme_stop_ns_queue(struct nvme_ns *ns) > { > if (!test_and_set_bit(NVME_NS_STOPPED, &ns->flags)) > - blk_mq_quiesce_queue(ns->queue); > - else > - blk_mq_wait_quiesce_done(ns->queue); > + blk_mq_quiesce_queue_nowait(ns->queue); > } > > /* > @@ -4620,6 +4618,11 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl) > down_read(&ctrl->namespaces_rwsem); > list_for_each_entry(ns, &ctrl->namespaces, list) > nvme_stop_ns_queue(ns); > + list_for_each_entry(ns, &ctrl->namespaces, list) { > + blk_mq_wait_quiesce_done(ns->queue); > + if (blk_mq_global_quiesce_wait(ns->queue)) > + break; > + } > up_read(&ctrl->namespaces_rwsem); Can you quantify how much of a difference it is to do rcu_read_unlock() for every queue? The big improvement here is that it is done in parallel instead of serially. Just wandering if it is worth the less than elegant interface...
On Mon, Nov 22, 2021 at 10:07:24AM +0200, Sagi Grimberg wrote: > > > On 11/19/21 4:18 AM, Ming Lei wrote: > > Chao Leng reported that in case of lots of namespaces, it may take quite a > > while for nvme_stop_queues() to quiesce all namespace queues. > > > > Improve nvme_stop_queues() by running quiesce in parallel, and just wait > > once if global quiesce wait is allowed. > > > > Link: https://lore.kernel.org/linux-block/cc732195-c053-9ce4-e1a7-e7f6dcf762ac@huawei.com/ > > Reported-by: Chao Leng <lengchao@huawei.com> > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > --- > > drivers/nvme/host/core.c | 9 ++++++--- > > 1 file changed, 6 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > > index 4b5de8f5435a..06741d3ed72b 100644 > > --- a/drivers/nvme/host/core.c > > +++ b/drivers/nvme/host/core.c > > @@ -4517,9 +4517,7 @@ static void nvme_start_ns_queue(struct nvme_ns *ns) > > static void nvme_stop_ns_queue(struct nvme_ns *ns) > > { > > if (!test_and_set_bit(NVME_NS_STOPPED, &ns->flags)) > > - blk_mq_quiesce_queue(ns->queue); > > - else > > - blk_mq_wait_quiesce_done(ns->queue); > > + blk_mq_quiesce_queue_nowait(ns->queue); > > } > > /* > > @@ -4620,6 +4618,11 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl) > > down_read(&ctrl->namespaces_rwsem); > > list_for_each_entry(ns, &ctrl->namespaces, list) > > nvme_stop_ns_queue(ns); > > + list_for_each_entry(ns, &ctrl->namespaces, list) { > > + blk_mq_wait_quiesce_done(ns->queue); > > + if (blk_mq_global_quiesce_wait(ns->queue)) > > + break; > > + } > > up_read(&ctrl->namespaces_rwsem); > > > Can you quantify how much of a difference it is to do rcu_read_unlock() > for every queue? The big improvement here is that it is done in parallel > instead of serially. Just wandering if it is worth the less than elegant > interface... The biggest improvement is N * synchronize_rcu() -> 1 * synchronize_rcu() in case of non blocking, that is what Chao Leng complained before. Even for blocking case, the parallel quiesce is still good, such as, when one synchronize_srcu() is done, other srcu syncs should be done usually too. thanks, Ming
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 4b5de8f5435a..06741d3ed72b 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4517,9 +4517,7 @@ static void nvme_start_ns_queue(struct nvme_ns *ns) static void nvme_stop_ns_queue(struct nvme_ns *ns) { if (!test_and_set_bit(NVME_NS_STOPPED, &ns->flags)) - blk_mq_quiesce_queue(ns->queue); - else - blk_mq_wait_quiesce_done(ns->queue); + blk_mq_quiesce_queue_nowait(ns->queue); } /* @@ -4620,6 +4618,11 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl) down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) nvme_stop_ns_queue(ns); + list_for_each_entry(ns, &ctrl->namespaces, list) { + blk_mq_wait_quiesce_done(ns->queue); + if (blk_mq_global_quiesce_wait(ns->queue)) + break; + } up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_stop_queues);
Chao Leng reported that in case of lots of namespaces, it may take quite a while for nvme_stop_queues() to quiesce all namespace queues. Improve nvme_stop_queues() by running quiesce in parallel, and just wait once if global quiesce wait is allowed. Link: https://lore.kernel.org/linux-block/cc732195-c053-9ce4-e1a7-e7f6dcf762ac@huawei.com/ Reported-by: Chao Leng <lengchao@huawei.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> --- drivers/nvme/host/core.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)