On Mon, Oct 09, 2017 at 07:24:24PM +0800, Ming Lei wrote: > During dispatching, we moved all requests from hctx->dispatch to > one temporary list, then dispatch them one by one from this list. > Unfortunately during this period, run queue from other contexts > may think the queue is idle, then start to dequeue from sw/scheduler > queue and still try to dispatch because ->dispatch is empty. This way > hurts sequential I/O performance because requests are dequeued when > lld queue is busy. > > This patch introduces the state of BLK_MQ_S_DISPATCH_BUSY to > make sure that request isn't dequeued until ->dispatch is > flushed. > > Reviewed-by: Bart Van Assche <bart.vanassche@xxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> I think this will do for now. Reviewed-by: Omar Sandoval <osandov@xxxxxx> > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > --- > block/blk-mq-debugfs.c | 1 + > block/blk-mq-sched.c | 38 ++++++++++++++++++++++++++++++++------ > block/blk-mq.c | 5 +++++ > include/linux/blk-mq.h | 1 + > 4 files changed, 39 insertions(+), 6 deletions(-)
