From fab58f7c545885b5cd0d6e70a9bccfd727ad7a9b Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sun, 9 Sep 2018 11:37:22 -0400 Subject: [PATCH] SUNRPC: Improve latency for interactive tasks One of the intentions with the priority queues was to ensure that no single process can hog the transport. The field task->tk_owner therefore identifies the RPC call's origin, and is intended to allow the RPC layer to organise queues for fairness. This commit therefore modifies the transmit queue to group requests by task->tk_owner, and ensures that we round robin among those groups. Signed-off-by: Trond Myklebust --- include/linux/sunrpc/xprt.h | 1 + net/sunrpc/xprt.c | 27 ++++++++++++++++++++++++--- 2 files changed, 25 insertions(+), 3 deletions(-) diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h index 8c2bb078f00cb..e377620b97440 100644 --- a/include/linux/sunrpc/xprt.h +++ b/include/linux/sunrpc/xprt.h @@ -89,6 +89,7 @@ struct rpc_rqst { }; struct list_head rq_xmit; /* Send queue */ + struct list_head rq_xmit2; /* Send queue */ void *rq_buffer; /* Call XDR encode buffer */ size_t rq_callsize; diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 9c5a8514d264b..44d0eeaddaac7 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1053,12 +1053,21 @@ xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req) void xprt_request_enqueue_transmit(struct rpc_task *task) { - struct rpc_rqst *req = task->tk_rqstp; + struct rpc_rqst *pos, *req = task->tk_rqstp; struct rpc_xprt *xprt = req->rq_xprt; if (xprt_request_need_enqueue_transmit(task, req)) { spin_lock(&xprt->queue_lock); + list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) { + if (pos->rq_task->tk_owner != task->tk_owner) + continue; + list_add_tail(&req->rq_xmit2, &pos->rq_xmit2); + INIT_LIST_HEAD(&req->rq_xmit); + goto out; + } list_add_tail(&req->rq_xmit, &xprt->xmit_queue); + INIT_LIST_HEAD(&req->rq_xmit2); +out: set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate); spin_unlock(&xprt->queue_lock); } @@ -1074,8 +1083,20 @@ xprt_request_enqueue_transmit(struct rpc_task *task) static void xprt_request_dequeue_transmit_locked(struct rpc_task *task) { - if (test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate)) - list_del(&task->tk_rqstp->rq_xmit); + struct rpc_rqst *req = task->tk_rqstp; + + if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate)) + return; + if (!list_empty(&req->rq_xmit)) { + list_del(&req->rq_xmit); + if (!list_empty(&req->rq_xmit2)) { + struct rpc_rqst *next = list_first_entry(&req->rq_xmit2, + struct rpc_rqst, rq_xmit2); + list_del(&req->rq_xmit2); + list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue); + } + } else + list_del(&req->rq_xmit2); } /** -- 2.39.5