blk-mq: Reduce blk_mq_hw_ctx size
Since the srcu structure is rather large (184 bytes on an x86-64 system with kernel debugging disabled), only allocate it if needed. Reported-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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0731967877
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@ -172,7 +172,7 @@ void blk_mq_quiesce_queue(struct request_queue *q)
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queue_for_each_hw_ctx(q, hctx, i) {
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if (hctx->flags & BLK_MQ_F_BLOCKING)
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synchronize_srcu(&hctx->queue_rq_srcu);
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synchronize_srcu(hctx->queue_rq_srcu);
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else
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rcu = true;
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}
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@ -1094,9 +1094,9 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
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} else {
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might_sleep();
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srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
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srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
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blk_mq_sched_dispatch_requests(hctx);
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srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
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srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
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}
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}
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@ -1505,9 +1505,9 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
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might_sleep();
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srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
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srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
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__blk_mq_try_issue_directly(hctx, rq, cookie, true);
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srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
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srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
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}
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}
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@ -1853,7 +1853,7 @@ static void blk_mq_exit_hctx(struct request_queue *q,
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set->ops->exit_hctx(hctx, hctx_idx);
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if (hctx->flags & BLK_MQ_F_BLOCKING)
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cleanup_srcu_struct(&hctx->queue_rq_srcu);
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cleanup_srcu_struct(hctx->queue_rq_srcu);
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blk_mq_remove_cpuhp(hctx);
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blk_free_flush_queue(hctx->fq);
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@ -1926,7 +1926,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
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goto free_fq;
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if (hctx->flags & BLK_MQ_F_BLOCKING)
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init_srcu_struct(&hctx->queue_rq_srcu);
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init_srcu_struct(hctx->queue_rq_srcu);
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blk_mq_debugfs_register_hctx(q, hctx);
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@ -2201,6 +2201,20 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
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}
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EXPORT_SYMBOL(blk_mq_init_queue);
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static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
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{
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int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
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BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, queue_rq_srcu),
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__alignof__(struct blk_mq_hw_ctx)) !=
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sizeof(struct blk_mq_hw_ctx));
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if (tag_set->flags & BLK_MQ_F_BLOCKING)
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hw_ctx_size += sizeof(struct srcu_struct);
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return hw_ctx_size;
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}
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static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
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struct request_queue *q)
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{
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@ -2215,7 +2229,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
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continue;
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node = blk_mq_hw_queue_to_node(q->mq_map, i);
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hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
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hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
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GFP_KERNEL, node);
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if (!hctxs[i])
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break;
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@ -39,8 +39,6 @@ struct blk_mq_hw_ctx {
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struct blk_mq_tags *tags;
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struct blk_mq_tags *sched_tags;
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struct srcu_struct queue_rq_srcu;
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unsigned long queued;
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unsigned long run;
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#define BLK_MQ_MAX_DISPATCH_ORDER 7
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@ -62,6 +60,9 @@ struct blk_mq_hw_ctx {
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struct dentry *debugfs_dir;
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struct dentry *sched_debugfs_dir;
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#endif
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/* Must be the last member - see also blk_mq_hw_ctx_size(). */
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struct srcu_struct queue_rq_srcu[0];
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};
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struct blk_mq_tag_set {
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