* [PATCH v4 0/2] improve quiesce time for large amount of namespaces @ 2020-07-27 22:07 Sagi Grimberg 2020-07-27 22:07 ` [PATCH v4 1/2] blk-mq: add async quiesce interface Sagi Grimberg 2020-07-27 22:07 ` [PATCH v4 2/2] nvme: improve quiesce time for large amount of namespaces Sagi Grimberg 0 siblings, 2 replies; 5+ messages in thread From: Sagi Grimberg @ 2020-07-27 22:07 UTC (permalink / raw) To: linux-nvme, Christoph Hellwig, Keith Busch, Jens Axboe Cc: linux-block, Ming Lin, Chao Leng This set improves the quiesce time when using a large set of namespaces, which also improves I/O failover time in a multipath environment. We improve for both non-blocking hctxs (e.g. pci, fc, rdma nvme transports) and blocking hctxs (e.g. tcp nvme transport) by splitting queue quiesce to blk_mq_quiesce_queue_async call_(s)rcu and blk_mq_quiesce_queue_async_wait to wait for it to complete. These calls are meant to be called in parallel for different queues. Changes from v3: - make hctx->rcu_sync dynamically allocated from the heap instead of a static member function Changes from v2: - made blk_mq_quiesce_queue_async operate on both blocking and non-blocking hctxs. - removed separation between blocking vs. non-blocking queues - dropeed patch from Chao - dropped nvme-rdma test patch Changes from v1: - trivial typo fixes Sagi Grimberg (2): blk-mq: add async quiesce interface nvme: improve quiesce time for large amount of namespaces block/blk-mq.c | 46 ++++++++++++++++++++++++++++++++++++++++ drivers/nvme/host/core.c | 4 +++- include/linux/blk-mq.h | 4 ++++ 3 files changed, 53 insertions(+), 1 deletion(-) -- 2.25.1 _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v4 1/2] blk-mq: add async quiesce interface 2020-07-27 22:07 [PATCH v4 0/2] improve quiesce time for large amount of namespaces Sagi Grimberg @ 2020-07-27 22:07 ` Sagi Grimberg 2020-07-27 22:13 ` Jens Axboe 2020-07-27 22:07 ` [PATCH v4 2/2] nvme: improve quiesce time for large amount of namespaces Sagi Grimberg 1 sibling, 1 reply; 5+ messages in thread From: Sagi Grimberg @ 2020-07-27 22:07 UTC (permalink / raw) To: linux-nvme, Christoph Hellwig, Keith Busch, Jens Axboe Cc: linux-block, Ming Lin, Chao Leng Drivers that may have to quiesce a large amount of request queues at once (e.g. controller or adapter reset). These drivers would benefit from an async quiesce interface such that the can trigger quiesce asynchronously and wait for all in parallel. This leaves the synchronization responsibility to the driver, but adds a convenient interface to quiesce async and wait in a single pass. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> --- block/blk-mq.c | 46 ++++++++++++++++++++++++++++++++++++++++++ include/linux/blk-mq.h | 4 ++++ 2 files changed, 50 insertions(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index abcf590f6238..d913924117d2 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -209,6 +209,52 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) } EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); +void blk_mq_quiesce_queue_async(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + int rcu = false; + + blk_mq_quiesce_queue_nowait(q); + + queue_for_each_hw_ctx(q, hctx, i) { + hctx->rcu_sync = kmalloc(sizeof(*hctx->rcu_sync), GFP_KERNEL); + if (!hctx->rcu_sync) { + /* fallback to serial rcu sync */ + if (hctx->flags & BLK_MQ_F_BLOCKING) + synchronize_srcu(hctx->srcu); + else + rcu = true; + } else { + init_completion(&hctx->rcu_sync->completion); + init_rcu_head(&hctx->rcu_sync->head); + if (hctx->flags & BLK_MQ_F_BLOCKING) + call_srcu(hctx->srcu, &hctx->rcu_sync->head, + wakeme_after_rcu); + else + call_rcu(&hctx->rcu_sync->head, + wakeme_after_rcu); + } + } + if (rcu) + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_async); + +void blk_mq_quiesce_queue_async_wait(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + + queue_for_each_hw_ctx(q, hctx, i) { + if (!hctx->rcu_sync) + continue; + wait_for_completion(&hctx->rcu_sync->completion); + destroy_rcu_head(&hctx->rcu_sync->head); + } +} +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_async_wait); + /** * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished * @q: request queue. diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 23230c1d031e..7213ce56bb31 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -5,6 +5,7 @@ #include <linux/blkdev.h> #include <linux/sbitmap.h> #include <linux/srcu.h> +#include <linux/rcupdate_wait.h> struct blk_mq_tags; struct blk_flush_queue; @@ -170,6 +171,7 @@ struct blk_mq_hw_ctx { */ struct list_head hctx_list; + struct rcu_synchronize *rcu_sync; /** * @srcu: Sleepable RCU. Use as lock when type of the hardware queue is * blocking (BLK_MQ_F_BLOCKING). Must be the last member - see also @@ -532,6 +534,8 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap); void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues); void blk_mq_quiesce_queue_nowait(struct request_queue *q); +void blk_mq_quiesce_queue_async(struct request_queue *q); +void blk_mq_quiesce_queue_async_wait(struct request_queue *q); unsigned int blk_mq_rq_cpu(struct request *rq); -- 2.25.1 _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v4 1/2] blk-mq: add async quiesce interface 2020-07-27 22:07 ` [PATCH v4 1/2] blk-mq: add async quiesce interface Sagi Grimberg @ 2020-07-27 22:13 ` Jens Axboe 2020-07-27 22:37 ` Sagi Grimberg 0 siblings, 1 reply; 5+ messages in thread From: Jens Axboe @ 2020-07-27 22:13 UTC (permalink / raw) To: Sagi Grimberg, linux-nvme, Christoph Hellwig, Keith Busch Cc: linux-block, Ming Lin, Chao Leng On 7/27/20 4:07 PM, Sagi Grimberg wrote: > Drivers that may have to quiesce a large amount of request queues at once > (e.g. controller or adapter reset). These drivers would benefit from an > async quiesce interface such that the can trigger quiesce asynchronously > and wait for all in parallel. > > This leaves the synchronization responsibility to the driver, but adds > a convenient interface to quiesce async and wait in a single pass. > > Signed-off-by: Sagi Grimberg <sagi@grimberg.me> > --- > block/blk-mq.c | 46 ++++++++++++++++++++++++++++++++++++++++++ > include/linux/blk-mq.h | 4 ++++ > 2 files changed, 50 insertions(+) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index abcf590f6238..d913924117d2 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -209,6 +209,52 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) > } > EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); > > +void blk_mq_quiesce_queue_async(struct request_queue *q) > +{ > + struct blk_mq_hw_ctx *hctx; > + unsigned int i; > + int rcu = false; > + > + blk_mq_quiesce_queue_nowait(q); > + > + queue_for_each_hw_ctx(q, hctx, i) { > + hctx->rcu_sync = kmalloc(sizeof(*hctx->rcu_sync), GFP_KERNEL); > + if (!hctx->rcu_sync) { > + /* fallback to serial rcu sync */ > + if (hctx->flags & BLK_MQ_F_BLOCKING) > + synchronize_srcu(hctx->srcu); > + else > + rcu = true; > + } else { > + init_completion(&hctx->rcu_sync->completion); > + init_rcu_head(&hctx->rcu_sync->head); > + if (hctx->flags & BLK_MQ_F_BLOCKING) > + call_srcu(hctx->srcu, &hctx->rcu_sync->head, > + wakeme_after_rcu); > + else > + call_rcu(&hctx->rcu_sync->head, > + wakeme_after_rcu); > + } > + } > + if (rcu) > + synchronize_rcu(); > +} > +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_async); This won't always be async, and that might matter to some users. I think it'd be better to put the fallback path into the _wait() part instead, since the caller should expect that to be blocking/waiting as the name implies. Nit picking, but... -- Jens Axboe _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v4 1/2] blk-mq: add async quiesce interface 2020-07-27 22:13 ` Jens Axboe @ 2020-07-27 22:37 ` Sagi Grimberg 0 siblings, 0 replies; 5+ messages in thread From: Sagi Grimberg @ 2020-07-27 22:37 UTC (permalink / raw) To: Jens Axboe, linux-nvme, Christoph Hellwig, Keith Busch Cc: linux-block, Ming Lin, Chao Leng >> +void blk_mq_quiesce_queue_async(struct request_queue *q) >> +{ >> + struct blk_mq_hw_ctx *hctx; >> + unsigned int i; >> + int rcu = false; >> + >> + blk_mq_quiesce_queue_nowait(q); >> + >> + queue_for_each_hw_ctx(q, hctx, i) { >> + hctx->rcu_sync = kmalloc(sizeof(*hctx->rcu_sync), GFP_KERNEL); >> + if (!hctx->rcu_sync) { >> + /* fallback to serial rcu sync */ >> + if (hctx->flags & BLK_MQ_F_BLOCKING) >> + synchronize_srcu(hctx->srcu); >> + else >> + rcu = true; >> + } else { >> + init_completion(&hctx->rcu_sync->completion); >> + init_rcu_head(&hctx->rcu_sync->head); >> + if (hctx->flags & BLK_MQ_F_BLOCKING) >> + call_srcu(hctx->srcu, &hctx->rcu_sync->head, >> + wakeme_after_rcu); >> + else >> + call_rcu(&hctx->rcu_sync->head, >> + wakeme_after_rcu); >> + } >> + } >> + if (rcu) >> + synchronize_rcu(); >> +} >> +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_async); > > This won't always be async, and that might matter to some users. I think > it'd be better to put the fallback path into the _wait() part instead, > since the caller should expect that to be blocking/waiting as the name > implies. > > Nit picking, but... Makes sense.. I thought more about Keith suggestion for an interface that accepts a tagset. It allows us to decide what we do based on the tagset itself which is now passed in the interface. What do you think about: -- diff --git a/block/blk-mq.c b/block/blk-mq.c index abcf590f6238..d4b24aa1a766 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -209,6 +209,43 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) } EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); +static void blk_mq_quiesce_queue_async(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + + blk_mq_quiesce_queue_nowait(q); + + queue_for_each_hw_ctx(q, hctx, i) { + if (!(hctx->flags & BLK_MQ_F_BLOCKING)) + continue; + + hctx->rcu_sync = kmalloc(sizeof(*hctx->rcu_sync), GFP_KERNEL); + if (!hctx->rcu_sync) + continue; + + init_completion(&hctx->rcu_sync->completion); + init_rcu_head(&hctx->rcu_sync->head); + call_srcu(hctx->srcu, &hctx->rcu_sync->head, + wakeme_after_rcu); + } +} + +static void blk_mq_quiesce_queue_async_wait(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + + queue_for_each_hw_ctx(q, hctx, i) { + if (!hctx->rcu_sync) { + synchronize_srcu(hctx->srcu); + continue; + } + wait_for_completion(&hctx->rcu_sync->completion); + destroy_rcu_head(&hctx->rcu_sync->head); + } +} + /** * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished * @q: request queue. @@ -2884,6 +2921,39 @@ static void queue_set_hctx_shared(struct request_queue *q, bool shared) } } +void blk_mq_quiesce_tagset(struct blk_mq_tag_set *set) +{ + struct request_queue *q; + + mutex_lock(&set->tag_list_lock); + list_for_each_entry(q, &set->tag_list, tag_set_list) { + if (!(set->flags & BLK_MQ_F_BLOCKING)) + blk_mq_quiesce_queue_nowait(q); + else + blk_mq_quiesce_queue_async(q); + } + + if (!(set->flags & BLK_MQ_F_BLOCKING)) { + synchronize_rcu(); + } else { + list_for_each_entry(q, &set->tag_list, tag_set_list) + blk_mq_quiesce_queue_async_wait(q); + } + mutex_unlock(&set->tag_list_lock); +} +EXPORT_SYMBOL_GPL(blk_mq_quiesce_tagset); + +void blk_mq_unquiesce_tagset(struct blk_mq_tag_set *set) +{ + struct request_queue *q; + + mutex_lock(&set->tag_list_lock); + list_for_each_entry(q, &set->tag_list, tag_set_list) + blk_mq_unquiesce_queue(q); + mutex_unlock(&set->tag_list_lock); +} +EXPORT_SYMBOL_GPL(blk_mq_unquiesce_tagset); + static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared) { diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 23230c1d031e..a85f2dedc947 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -5,6 +5,7 @@ #include <linux/blkdev.h> #include <linux/sbitmap.h> #include <linux/srcu.h> +#include <linux/rcupdate_wait.h> struct blk_mq_tags; struct blk_flush_queue; @@ -170,6 +171,7 @@ struct blk_mq_hw_ctx { */ struct list_head hctx_list; + struct rcu_synchronize *rcu_sync; /** * @srcu: Sleepable RCU. Use as lock when type of the hardware queue is * blocking (BLK_MQ_F_BLOCKING). Must be the last member - see also @@ -532,6 +534,8 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap); void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues); void blk_mq_quiesce_queue_nowait(struct request_queue *q); +void blk_mq_quiesce_tagset(struct request_queue *q); +void blk_mq_unquiesce_tagset(struct request_queue *q); unsigned int blk_mq_rq_cpu(struct request *rq); -- And then nvme will use it: -- diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 05aa568a60af..c41df20996d7 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4557,23 +4557,13 @@ EXPORT_SYMBOL_GPL(nvme_start_freeze); void nvme_stop_queues(struct nvme_ctrl *ctrl) { - struct nvme_ns *ns; - - down_read(&ctrl->namespaces_rwsem); - list_for_each_entry(ns, &ctrl->namespaces, list) - blk_mq_quiesce_queue(ns->queue); - up_read(&ctrl->namespaces_rwsem); + blk_mq_quiesce_tagset(ctrl->tagset); } EXPORT_SYMBOL_GPL(nvme_stop_queues); void nvme_start_queues(struct nvme_ctrl *ctrl) { - struct nvme_ns *ns; - - down_read(&ctrl->namespaces_rwsem); - list_for_each_entry(ns, &ctrl->namespaces, list) - blk_mq_unquiesce_queue(ns->queue); - up_read(&ctrl->namespaces_rwsem); + blk_mq_unquiesce_tagset(ctrl->tagset); } EXPORT_SYMBOL_GPL(nvme_start_queues); -- Thoughts? _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v4 2/2] nvme: improve quiesce time for large amount of namespaces 2020-07-27 22:07 [PATCH v4 0/2] improve quiesce time for large amount of namespaces Sagi Grimberg 2020-07-27 22:07 ` [PATCH v4 1/2] blk-mq: add async quiesce interface Sagi Grimberg @ 2020-07-27 22:07 ` Sagi Grimberg 1 sibling, 0 replies; 5+ messages in thread From: Sagi Grimberg @ 2020-07-27 22:07 UTC (permalink / raw) To: linux-nvme, Christoph Hellwig, Keith Busch, Jens Axboe Cc: linux-block, Ming Lin, Chao Leng nvme currently will synchronize queue quiesce for each namespace at once. This can slow down failover time (which first quiesce all ns queues) if we have a large amount of namespaces. Instead, we want to use an async interface and do the namespaces quiesce in parallel rather than serially. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> --- drivers/nvme/host/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 05aa568a60af..e8cc728dee46 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4561,7 +4561,9 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl) down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) - blk_mq_quiesce_queue(ns->queue); + blk_mq_quiesce_queue_async(ns->queue); + list_for_each_entry(ns, &ctrl->namespaces, list) + blk_mq_quiesce_queue_async_wait(ns->queue); up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_stop_queues); -- 2.25.1 _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme ^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-07-27 22:37 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-07-27 22:07 [PATCH v4 0/2] improve quiesce time for large amount of namespaces Sagi Grimberg 2020-07-27 22:07 ` [PATCH v4 1/2] blk-mq: add async quiesce interface Sagi Grimberg 2020-07-27 22:13 ` Jens Axboe 2020-07-27 22:37 ` Sagi Grimberg 2020-07-27 22:07 ` [PATCH v4 2/2] nvme: improve quiesce time for large amount of namespaces Sagi Grimberg
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