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authorTrond Myklebust <trond.myklebust@hammerspace.com>2021-07-12 09:52:59 -0400
committerTrond Myklebust <trond.myklebust@hammerspace.com>2021-10-03 20:49:05 -0400
commitea7a1019d8baf8503ecd6e3ec8436dec283569e6 (patch)
tree510a00c01d7b8e77dbcd93baf90256fcba09126f /net/sunrpc
parentca05cbae2a0468e5d78e9b4605936a8bf5da328b (diff)
downloadlinux-ea7a1019d8baf8503ecd6e3ec8436dec283569e6.tar.bz2
SUNRPC: Partial revert of commit 6f9f17287e78
The premise of commit 6f9f17287e78 ("SUNRPC: Mitigate cond_resched() in xprt_transmit()") was that cond_resched() is expensive and unnecessary when there has been just a single send. The point of cond_resched() is to ensure that tasks that should pre-empt this one get a chance to do so when it is safe to do so. The code prior to commit 6f9f17287e78 failed to take into account that it was keeping a rpc_task pinned for longer than it needed to, and so rather than doing a full revert, let's just move the cond_resched. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/xprt.c28
1 files changed, 15 insertions, 13 deletions
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index cfd681700d1a..d4aeee83763e 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1603,15 +1603,14 @@ xprt_transmit(struct rpc_task *task)
{
struct rpc_rqst *next, *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
- int counter, status;
+ int status;
spin_lock(&xprt->queue_lock);
- counter = 0;
- while (!list_empty(&xprt->xmit_queue)) {
- if (++counter == 20)
+ for (;;) {
+ next = list_first_entry_or_null(&xprt->xmit_queue,
+ struct rpc_rqst, rq_xmit);
+ if (!next)
break;
- next = list_first_entry(&xprt->xmit_queue,
- struct rpc_rqst, rq_xmit);
xprt_pin_rqst(next);
spin_unlock(&xprt->queue_lock);
status = xprt_request_transmit(next, task);
@@ -1619,13 +1618,16 @@ xprt_transmit(struct rpc_task *task)
status = 0;
spin_lock(&xprt->queue_lock);
xprt_unpin_rqst(next);
- if (status == 0) {
- if (!xprt_request_data_received(task) ||
- test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
- continue;
- } else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
- task->tk_status = status;
- break;
+ if (status < 0) {
+ if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+ task->tk_status = status;
+ break;
+ }
+ /* Was @task transmitted, and has it received a reply? */
+ if (xprt_request_data_received(task) &&
+ !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+ break;
+ cond_resched_lock(&xprt->queue_lock);
}
spin_unlock(&xprt->queue_lock);
}