From: Bart Van Assche <Bart.VanAssche@sandisk.com> To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>, "axboe@fb.com" <axboe@fb.com> Cc: "osandov@osandov.com" <osandov@osandov.com> Subject: Re: [PATCH 08/10] blk-mq-sched: add framework for MQ capable IO schedulers Date: Thu, 12 Jan 2017 21:45:16 +0000 [thread overview] Message-ID: <1484257502.2720.21.camel@sandisk.com> (raw) In-Reply-To: <1484170803-9311-9-git-send-email-axboe@fb.com> On Wed, 2017-01-11 at 14:40 -0700, Jens Axboe wrote: > @@ -451,11 +456,11 @@ void blk_insert_flush(struct request *rq) > * processed directly without going through flush machinery. Queue > * for normal execution. > */ > - if ((policy & REQ_FSEQ_DATA) && > - !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { > - if (q->mq_ops) { > - blk_mq_insert_request(rq, false, true, false); > - } else > + if (((policy & REQ_FSEQ_DATA) && > + !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH)))) { > + if (q->mq_ops) > + blk_mq_sched_insert_request(rq, false, true, false); > + else > list_add_tail(&rq->queuelist, &q->queue_head); > return; > } Not that it really matters, but this change adds a pair of parentheses -- "if (e)" is changed into "if ((e))". Is this necessary? > +void blk_mq_sched_free_hctx_data(struct request_queue *q, > + void (*exit)(struct blk_mq_hw_ctx *)) > +{ > + struct blk_mq_hw_ctx *hctx; > + int i; > + > + queue_for_each_hw_ctx(q, hctx, i) { > + if (exit) > + exit(hctx); > + kfree(hctx->sched_data); > + hctx->sched_data =3D NULL; > + } > +} > +EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data); > + > +int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size, > + int (*init)(struct blk_mq_hw_ctx *), > + void (*exit)(struct blk_mq_hw_ctx *)) > +{ > + struct blk_mq_hw_ctx *hctx; > + int ret; > + int i; > + > + queue_for_each_hw_ctx(q, hctx, i) { > + hctx->sched_data =3D kmalloc_node(size, GFP_KERNEL, hctx->numa_node); > + if (!hctx->sched_data) { > + ret =3D -ENOMEM; > + goto error; > + } > + > + if (init) { > + ret =3D init(hctx); > + if (ret) { > + /* > + * We don't want to give exit() a partially > + * initialized sched_data. init() must clean up > + * if it fails. > + */ > + kfree(hctx->sched_data); > + hctx->sched_data =3D NULL; > + goto error; > + } > + } > + } > + > + return 0; > +error: > + blk_mq_sched_free_hctx_data(q, exit); > + return ret; > +} If one of the init() calls by blk_mq_sched_init_hctx_data() fails then blk_mq_sched_free_hctx_data() will call exit() even for hctx's for which init() has not been called. How about changing "if (exit)" into "if (exit &= & hctx->sched_data)" such that exit() is only called for hctx's for which init() has been called? > +struct request *blk_mq_sched_get_request(struct request_queue *q, > + struct bio *bio, > + unsigned int op, > + struct blk_mq_alloc_data *data) > +{ > + struct elevator_queue *e =3D q->elevator; > + struct blk_mq_hw_ctx *hctx; > + struct blk_mq_ctx *ctx; > + struct request *rq; > + > + blk_queue_enter_live(q); > + ctx =3D blk_mq_get_ctx(q); > + hctx =3D blk_mq_map_queue(q, ctx->cpu); > + > + blk_mq_set_alloc_data(data, q, 0, ctx, hctx); > + > + if (e) { > + data->flags |=3D BLK_MQ_REQ_INTERNAL; > + if (e->type->ops.mq.get_request) > + rq =3D e->type->ops.mq.get_request(q, op, data); > + else > + rq =3D __blk_mq_alloc_request(data, op); > + } else { > + rq =3D __blk_mq_alloc_request(data, op); > + if (rq) { > + rq->tag =3D rq->internal_tag; > + rq->internal_tag =3D -1; > + } > + } > + > + if (rq) { > + rq->elv.icq =3D NULL; > + if (e && e->type->icq_cache) > + blk_mq_sched_assign_ioc(q, rq, bio); > + data->hctx->queued++; > + return rq; > + } > + > + blk_queue_exit(q); > + return NULL; > +} The "rq->tag =3D rq->internal_tag; rq->internal_tag =3D -1;" occurs not onl= y here but also in blk_mq_alloc_request_hctx(). Has it been considered to mov= e that code into __blk_mq_alloc_request()? @@ -223,14 +225,17 @@ struct request *__blk_mq_alloc_request(struct blk_mq_= alloc_data *data, > =20 > tag =3D blk_mq_get_tag(data); > if (tag !=3D BLK_MQ_TAG_FAIL) { > - rq =3D data->hctx->tags->rqs[tag]; > + struct blk_mq_tags *tags =3D blk_mq_tags_from_data(data); > + > + rq =3D tags->rqs[tag]; > =20 > if (blk_mq_tag_busy(data->hctx)) { > rq->rq_flags =3D RQF_MQ_INFLIGHT; > atomic_inc(&data->hctx->nr_active); > } > =20 > - rq->tag =3D tag; > + rq->tag =3D -1; > + rq->internal_tag =3D tag; > blk_mq_rq_ctx_init(data->q, data->ctx, rq, op); > return rq; > } How about using the following code for tag assignment instead of "rq->tag = =3D -1; rq->internal_tag =3D tag"? if (data->flags & BLK_MQ_REQ_INTERNAL) { rq->tag =3D -1; rq->internal_tag =3D tag; } else { rq->tag =3D tag; rq->internal_tag =3D -1; } > @@ -313,6 +313,9 @@ struct request *blk_mq_alloc_request_hctx(struct requ= est_queue *q, int rw, > goto out_queue_exit; > } > =20 > + rq->tag =3D rq->internal_tag; > + rq->internal_tag =3D -1; > + > return rq; > =20 > out_queue_exit: > @@ -321,10 +324,10 @@ struct request *blk_mq_alloc_request_hctx(struct re= quest_queue *q, int rw, > } > EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx); Should something like "WARN_ON_ONCE(flags & BLK_MQ_REQ_INTERNAL)" be added at the start of this function to avoid that BLK_MQ_REQ_INTERNAL is passed i= n from outside the block layer? Bart.=
WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <Bart.VanAssche@sandisk.com> To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>, "axboe@fb.com" <axboe@fb.com> Cc: "osandov@osandov.com" <osandov@osandov.com> Subject: Re: [PATCH 08/10] blk-mq-sched: add framework for MQ capable IO schedulers Date: Thu, 12 Jan 2017 21:45:16 +0000 [thread overview] Message-ID: <1484257502.2720.21.camel@sandisk.com> (raw) In-Reply-To: <1484170803-9311-9-git-send-email-axboe@fb.com> On Wed, 2017-01-11 at 14:40 -0700, Jens Axboe wrote: > @@ -451,11 +456,11 @@ void blk_insert_flush(struct request *rq) > * processed directly without going through flush machinery. Queue > * for normal execution. > */ > - if ((policy & REQ_FSEQ_DATA) && > - !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { > - if (q->mq_ops) { > - blk_mq_insert_request(rq, false, true, false); > - } else > + if (((policy & REQ_FSEQ_DATA) && > + !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH)))) { > + if (q->mq_ops) > + blk_mq_sched_insert_request(rq, false, true, false); > + else > list_add_tail(&rq->queuelist, &q->queue_head); > return; > } Not that it really matters, but this change adds a pair of parentheses -- "if (e)" is changed into "if ((e))". Is this necessary? > +void blk_mq_sched_free_hctx_data(struct request_queue *q, > + void (*exit)(struct blk_mq_hw_ctx *)) > +{ > + struct blk_mq_hw_ctx *hctx; > + int i; > + > + queue_for_each_hw_ctx(q, hctx, i) { > + if (exit) > + exit(hctx); > + kfree(hctx->sched_data); > + hctx->sched_data = NULL; > + } > +} > +EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data); > + > +int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size, > + int (*init)(struct blk_mq_hw_ctx *), > + void (*exit)(struct blk_mq_hw_ctx *)) > +{ > + struct blk_mq_hw_ctx *hctx; > + int ret; > + int i; > + > + queue_for_each_hw_ctx(q, hctx, i) { > + hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node); > + if (!hctx->sched_data) { > + ret = -ENOMEM; > + goto error; > + } > + > + if (init) { > + ret = init(hctx); > + if (ret) { > + /* > + * We don't want to give exit() a partially > + * initialized sched_data. init() must clean up > + * if it fails. > + */ > + kfree(hctx->sched_data); > + hctx->sched_data = NULL; > + goto error; > + } > + } > + } > + > + return 0; > +error: > + blk_mq_sched_free_hctx_data(q, exit); > + return ret; > +} If one of the init() calls by blk_mq_sched_init_hctx_data() fails then blk_mq_sched_free_hctx_data() will call exit() even for hctx's for which init() has not been called. How about changing "if (exit)" into "if (exit && hctx->sched_data)" such that exit() is only called for hctx's for which init() has been called? > +struct request *blk_mq_sched_get_request(struct request_queue *q, > + struct bio *bio, > + unsigned int op, > + struct blk_mq_alloc_data *data) > +{ > + struct elevator_queue *e = q->elevator; > + struct blk_mq_hw_ctx *hctx; > + struct blk_mq_ctx *ctx; > + struct request *rq; > + > + blk_queue_enter_live(q); > + ctx = blk_mq_get_ctx(q); > + hctx = blk_mq_map_queue(q, ctx->cpu); > + > + blk_mq_set_alloc_data(data, q, 0, ctx, hctx); > + > + if (e) { > + data->flags |= BLK_MQ_REQ_INTERNAL; > + if (e->type->ops.mq.get_request) > + rq = e->type->ops.mq.get_request(q, op, data); > + else > + rq = __blk_mq_alloc_request(data, op); > + } else { > + rq = __blk_mq_alloc_request(data, op); > + if (rq) { > + rq->tag = rq->internal_tag; > + rq->internal_tag = -1; > + } > + } > + > + if (rq) { > + rq->elv.icq = NULL; > + if (e && e->type->icq_cache) > + blk_mq_sched_assign_ioc(q, rq, bio); > + data->hctx->queued++; > + return rq; > + } > + > + blk_queue_exit(q); > + return NULL; > +} The "rq->tag = rq->internal_tag; rq->internal_tag = -1;" occurs not only here but also in blk_mq_alloc_request_hctx(). Has it been considered to move that code into __blk_mq_alloc_request()? @@ -223,14 +225,17 @@ struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data, > > tag = blk_mq_get_tag(data); > if (tag != BLK_MQ_TAG_FAIL) { > - rq = data->hctx->tags->rqs[tag]; > + struct blk_mq_tags *tags = blk_mq_tags_from_data(data); > + > + rq = tags->rqs[tag]; > > if (blk_mq_tag_busy(data->hctx)) { > rq->rq_flags = RQF_MQ_INFLIGHT; > atomic_inc(&data->hctx->nr_active); > } > > - rq->tag = tag; > + rq->tag = -1; > + rq->internal_tag = tag; > blk_mq_rq_ctx_init(data->q, data->ctx, rq, op); > return rq; > } How about using the following code for tag assignment instead of "rq->tag = -1; rq->internal_tag = tag"? if (data->flags & BLK_MQ_REQ_INTERNAL) { rq->tag = -1; rq->internal_tag = tag; } else { rq->tag = tag; rq->internal_tag = -1; } > @@ -313,6 +313,9 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw, > goto out_queue_exit; > } > > + rq->tag = rq->internal_tag; > + rq->internal_tag = -1; > + > return rq; > > out_queue_exit: > @@ -321,10 +324,10 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw, > } > EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx); Should something like "WARN_ON_ONCE(flags & BLK_MQ_REQ_INTERNAL)" be added at the start of this function to avoid that BLK_MQ_REQ_INTERNAL is passed in from outside the block layer? Bart.
next prev parent reply other threads:[~2017-01-12 21:45 UTC|newest] Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-11 21:39 [PATCHSET v6] blk-mq scheduling framework Jens Axboe 2017-01-11 21:39 ` [PATCH 01/10] block: move existing elevator ops to union Jens Axboe 2017-01-12 10:15 ` Johannes Thumshirn 2017-01-12 10:15 ` Johannes Thumshirn 2017-01-12 21:17 ` Bart Van Assche 2017-01-12 21:17 ` Bart Van Assche 2017-01-13 8:34 ` Christoph Hellwig 2017-01-13 15:00 ` Jens Axboe 2017-01-11 21:39 ` [PATCH 02/10] blk-mq: make mq_ops a const pointer Jens Axboe 2017-01-12 10:14 ` Johannes Thumshirn 2017-01-12 10:14 ` Johannes Thumshirn 2017-01-13 8:16 ` Christoph Hellwig 2017-01-11 21:39 ` [PATCH 03/10] block: move rq_ioc() to blk.h Jens Axboe 2017-01-12 10:14 ` Johannes Thumshirn 2017-01-12 10:14 ` Johannes Thumshirn 2017-01-12 21:18 ` Bart Van Assche 2017-01-12 21:18 ` Bart Van Assche 2017-01-13 8:33 ` Christoph Hellwig 2017-01-11 21:39 ` [PATCH 04/10] blk-mq: un-export blk_mq_free_hctx_request() Jens Axboe 2017-01-12 10:13 ` Johannes Thumshirn 2017-01-12 10:13 ` Johannes Thumshirn 2017-01-12 21:18 ` Bart Van Assche 2017-01-12 21:18 ` Bart Van Assche 2017-01-13 8:16 ` Christoph Hellwig 2017-01-11 21:39 ` [PATCH 05/10] blk-mq: export some helpers we need to the scheduling framework Jens Axboe 2017-01-12 10:17 ` Johannes Thumshirn 2017-01-12 10:17 ` Johannes Thumshirn 2017-01-12 21:20 ` Bart Van Assche 2017-01-12 21:20 ` Bart Van Assche 2017-01-13 8:17 ` Christoph Hellwig 2017-01-13 15:01 ` Jens Axboe 2017-01-11 21:39 ` [PATCH 06/10] blk-mq-tag: cleanup the normal/reserved tag allocation Jens Axboe 2017-01-12 21:22 ` Bart Van Assche 2017-01-12 21:22 ` Bart Van Assche 2017-01-12 22:07 ` Jens Axboe 2017-01-13 8:30 ` Christoph Hellwig 2017-01-13 15:06 ` Jens Axboe 2017-01-11 21:40 ` [PATCH 07/10] blk-mq: abstract out helpers for allocating/freeing tag maps Jens Axboe 2017-01-12 21:29 ` Bart Van Assche 2017-01-12 21:29 ` Bart Van Assche 2017-01-12 21:54 ` Jens Axboe 2017-01-13 8:25 ` Johannes Thumshirn 2017-01-13 8:25 ` Johannes Thumshirn 2017-01-11 21:40 ` [PATCH 08/10] blk-mq-sched: add framework for MQ capable IO schedulers Jens Axboe 2017-01-12 21:45 ` Bart Van Assche [this message] 2017-01-12 21:45 ` Bart Van Assche 2017-01-12 21:59 ` Jens Axboe 2017-01-13 11:15 ` Hannes Reinecke 2017-01-13 11:15 ` Hannes Reinecke 2017-01-13 16:39 ` Bart Van Assche 2017-01-13 16:39 ` Bart Van Assche 2017-01-13 16:41 ` Omar Sandoval 2017-01-13 17:43 ` Hannes Reinecke 2017-01-13 17:43 ` Hannes Reinecke 2017-01-11 21:40 ` [PATCH 09/10] mq-deadline: add blk-mq adaptation of the deadline IO scheduler Jens Axboe 2017-01-12 21:53 ` Bart Van Assche 2017-01-12 21:53 ` Bart Van Assche 2017-01-11 21:40 ` [PATCH 10/10] blk-mq-sched: allow setting of default " Jens Axboe 2017-01-12 21:54 ` Bart Van Assche 2017-01-12 21:54 ` Bart Van Assche 2017-01-12 21:16 ` [PATCHSET v6] blk-mq scheduling framework Bart Van Assche 2017-01-12 21:16 ` Bart Van Assche 2017-01-13 8:15 ` Hannes Reinecke 2017-01-13 8:15 ` Hannes Reinecke 2017-01-13 11:04 ` Hannes Reinecke 2017-01-13 11:04 ` Hannes Reinecke 2017-01-13 12:10 ` Hannes Reinecke 2017-01-13 12:10 ` Hannes Reinecke 2017-01-13 15:05 ` Jens Axboe 2017-01-13 15:03 ` Jens Axboe 2017-01-13 15:23 ` Jens Axboe 2017-01-13 15:23 ` Jens Axboe 2017-01-13 15:33 ` Hannes Reinecke 2017-01-13 15:33 ` Hannes Reinecke 2017-01-13 15:34 ` Jens Axboe 2017-01-13 15:34 ` Jens Axboe 2017-01-13 15:59 ` Hannes Reinecke 2017-01-13 15:59 ` Hannes Reinecke 2017-01-13 16:00 ` Jens Axboe 2017-01-13 16:00 ` Jens Axboe 2017-01-13 16:02 ` Jens Axboe 2017-01-13 21:45 ` Jens Axboe 2017-01-16 8:11 ` Hannes Reinecke 2017-01-16 8:11 ` Hannes Reinecke 2017-01-16 15:12 ` Jens Axboe 2017-01-16 15:16 ` Jens Axboe 2017-01-16 15:47 ` Jens Axboe 2017-01-13 10:09 ` Hannes Reinecke 2017-01-13 10:09 ` Hannes Reinecke 2017-01-15 10:12 ` Paolo Valente 2017-01-15 10:12 ` Paolo Valente 2017-01-15 15:55 ` Jens Axboe 2017-01-15 15:55 ` Jens Axboe
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