From 3110fc79606fb6003949246c6fb325dd43445273 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 30 Oct 2018 12:24:04 -0600 Subject: blk-mq: improve plug list sorting Currently we only look at the software queue, but with support for multiple maps, we should also look at the hardware queue. This is important since we'll flush out the request list if either the software queue or hardware queue don't match. This sorts by software queue first, then hardware queue if that differs. Finally we sort by request location like before. This minimizes the flush points per plug list. Reviewed-by: Keith Busch Reviewed-by: Sagi Grimberg Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe --- block/blk-mq.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) (limited to 'block') diff --git a/block/blk-mq.c b/block/blk-mq.c index 271726d48003..45c92b8d4795 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1612,14 +1612,21 @@ void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx, spin_unlock(&ctx->lock); } -static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b) +static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) { struct request *rqa = container_of(a, struct request, queuelist); struct request *rqb = container_of(b, struct request, queuelist); - return !(rqa->mq_ctx < rqb->mq_ctx || - (rqa->mq_ctx == rqb->mq_ctx && - blk_rq_pos(rqa) < blk_rq_pos(rqb))); + if (rqa->mq_ctx < rqb->mq_ctx) + return -1; + else if (rqa->mq_ctx > rqb->mq_ctx) + return 1; + else if (rqa->mq_hctx < rqb->mq_hctx) + return -1; + else if (rqa->mq_hctx > rqb->mq_hctx) + return 1; + + return blk_rq_pos(rqa) > blk_rq_pos(rqb); } void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) @@ -1634,7 +1641,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) list_splice_init(&plug->mq_list, &list); - list_sort(NULL, &list, plug_ctx_cmp); + list_sort(NULL, &list, plug_rq_cmp); this_q = NULL; this_hctx = NULL; -- cgit v1.2.3