blk-mq针对上面的问题给的解决方案核心点是将原来的request queue拆成了2部分 一是per-core的software queues, 数据类型blk_mq_ctx, 一般叫做ctx 一是跟硬件队列相关的dispatch queues, 数据类型blk_mq_hw_ctx, 一般叫做hctx none iosched blk-mq最核心的思想都体现在了none iosched上, 虽然none连自己的struct ...
blk_mq_alloc_tag_set: 为一个或者多个请求队列分配tag和request集合(tag set可以是多个request queue共享的,例如UFS设备,一个host controller只有一个tag set,但器件可能划分成多个LU--Logical Unit,每个LU有单独的request queue, 这些不同的request queue共享一个tag set),主要流程如下: 设置硬件队列数量(nr_hw_...
blk-mq is using preempt_disable/enable in order to ensure that the queue runners are placed on the right CPU. This does not work with the RT patches, because __blk_mq_run_hw_queue takes a non-raw spinlock with the preemption-disabled region. If there is contention on the lock, this ...
> void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) Are you sure this patch is sufficient? What prevents that blk_mq_run_hw_queues() gets called after the blk_mq_quiesce() and blk_sync_queue() calls have finished and before the queue is unfrozen? Ba...
blk_mq_insert_request(rq, 0); blk_mq_run_hw_queue(hctx, false); return; @@ -2983,7 +2988,7 @@ void blk_mq_submit_bio(struct bio *bio) } hctx = rq->mq_hctx; if ((rq->rq_flags & RQF_ELV) || if ((rq->rq_flags & RQF_USE_SCHED) || (hctx->dispatch_busy && (q...
Blk-mq(Block Multi-Queue):Linux内核引入了Blk-mq框架,支持多队列块设备驱动; 队列映射:每个CPU核心有一个独立的队列,避免了锁竞争。 优点: 充分利用多核CPU的性能; 减少锁竞争,提高并发性能。 这些策略共同作用,使得Linux内核能够高效地管理块设备的I/O操作,充分发挥硬件性能。
> insert requests to sw queue or scheduler queue > blk_mq_run_hw_queue > > Because of concurrent run queue, all requests inserted above may be > completed before calling the above blk_mq_run_hw_queue. Then queue can > be freed during the above blk_mq_run_hw_queue(). ...
blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q); blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q); blk_queue_flag_set(QUEUE_FLAG_DYING, q); /* * Drain all requests queued before DYING marking. Set DEAD flag to * prevent that blk_mq_run_hw_queues() accesses the hardware queues ...
这个request_queue 的初始化过程在 blk_mq_init_queue 中。它会调用 blk_mq_init_allocated_queue->blk_queue_make_request。在这里面,我们可以将 make_request_fn 函数设置为 blk_mq_make_request,也就是说,一旦上层有写入请求,我们就通过 blk_mq_make_request 这个函数,将请求放入 request_queue 队列中。
Check if multi-queue is enabled in your VM: Copy code snippet Copied to Clipboard Error: Could not Copy Copied to Clipboard Error: Could not Copy $ ls /sys/block/vda/mq 0 1 10 11 12 13 14 15 2 3 4 5 6 7 8 9 Check for the I/O thread: ...