This is a note to let you know that I've just added the patch titled SUNRPC: Mitigate cond_resched() in xprt_transmit() to the 5.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sunrpc-mitigate-cond_resched-in-xprt_transmit.patch and it can be found in the queue-5.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit cf002bbdab73a1193931266927c9d0f42c4a1086 Author: Chuck Lever <chuck.lever@xxxxxxxxxx> Date: Wed Jul 8 16:09:53 2020 -0400 SUNRPC: Mitigate cond_resched() in xprt_transmit() [ Upstream commit 6f9f17287e78e5049931af2037b15b26d134a32a ] The original purpose of this expensive call is to prevent a long queue of requests from blocking other work. The cond_resched() call is unnecessary after just a single send operation. For longer queues, instead of invoking the kernel scheduler, simply release the transport send lock and return to the RPC scheduler. Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 5a8e47bbfb9f4..13fbc2dd4196a 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1520,10 +1520,13 @@ xprt_transmit(struct rpc_task *task) { struct rpc_rqst *next, *req = task->tk_rqstp; struct rpc_xprt *xprt = req->rq_xprt; - int status; + int counter, status; spin_lock(&xprt->queue_lock); + counter = 0; while (!list_empty(&xprt->xmit_queue)) { + if (++counter == 20) + break; next = list_first_entry(&xprt->xmit_queue, struct rpc_rqst, rq_xmit); xprt_pin_rqst(next); @@ -1531,7 +1534,6 @@ xprt_transmit(struct rpc_task *task) status = xprt_request_transmit(next, task); if (status == -EBADMSG && next != req) status = 0; - cond_resched(); spin_lock(&xprt->queue_lock); xprt_unpin_rqst(next); if (status == 0) {