From: NeilBrown <neilb@suse.de>
To: Trond Myklebust <trond.myklebust@hammerspace.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
Chuck Lever <chuck.lever@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>
Cc: linux-nfs@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 07/13] SUNRPC: remove scheduling boost for "SWAPPER" tasks.
Date: Tue, 16 Nov 2021 13:44:04 +1100 [thread overview]
Message-ID: <163703064454.25805.6702162055736458441.stgit@noble.brown> (raw)
In-Reply-To: <163702956672.25805.16457749992977493579.stgit@noble.brown>
Currently, tasks marked as "swapper" tasks get put to the front of
non-priority rpc_queues, and are sorted earlier than non-swapper tasks on
the transport's ->xmit_queue.
This is pointless as currently *all* tasks for a mount that has swap
enabled on *any* file are marked as "swapper" tasks. So the net result
is that the non-priority rpc_queues are reverse-ordered (LIFO).
This scheduling boost is not necessary to avoid deadlocks, and hurts
fairness, so remove it. If there were a need to expedite some requests,
the tk_priority mechanism is a more appropriate tool.
Signed-off-by: NeilBrown <neilb@suse.de>
---
net/sunrpc/sched.c | 7 -------
net/sunrpc/xprt.c | 11 -----------
2 files changed, 18 deletions(-)
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index d5b6e897f5a5..256302bf6557 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -186,11 +186,6 @@ static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
/*
* Add new request to wait queue.
- *
- * Swapper tasks always get inserted at the head of the queue.
- * This should avoid many nasty memory deadlocks and hopefully
- * improve overall performance.
- * Everyone else gets appended to the queue to ensure proper FIFO behavior.
*/
static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
struct rpc_task *task,
@@ -199,8 +194,6 @@ static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
INIT_LIST_HEAD(&task->u.tk_wait.timer_list);
if (RPC_IS_PRIORITY(queue))
__rpc_add_wait_queue_priority(queue, task, queue_priority);
- else if (RPC_IS_SWAPPER(task))
- list_add(&task->u.tk_wait.list, &queue->tasks[0]);
else
list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
task->tk_waitqueue = queue;
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 47d207e416ab..a0a2583fe941 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1354,17 +1354,6 @@ xprt_request_enqueue_transmit(struct rpc_task *task)
INIT_LIST_HEAD(&req->rq_xmit2);
goto out;
}
- } else if (RPC_IS_SWAPPER(task)) {
- list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
- if (pos->rq_cong || pos->rq_bytes_sent)
- continue;
- if (RPC_IS_SWAPPER(pos->rq_task))
- continue;
- /* Note: req is added _before_ pos */
- list_add_tail(&req->rq_xmit, &pos->rq_xmit);
- INIT_LIST_HEAD(&req->rq_xmit2);
- goto out;
- }
} else if (!req->rq_seqno) {
list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
if (pos->rq_task->tk_owner != task->tk_owner)
next prev parent reply other threads:[~2021-11-16 2:50 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-16 2:44 [PATCH 00/13] Repair SWAP-over-NFS NeilBrown
2021-11-16 2:44 ` [PATCH 09/13] SUNRPC: improve 'swap' handling: scheduling and PF_MEMALLOC NeilBrown
2021-11-16 2:44 ` [PATCH 11/13] NFS: swap-out must always use STABLE writes NeilBrown
2021-11-16 2:44 ` [PATCH 02/13] NFS: do not take i_rwsem for swap IO NeilBrown
2021-11-16 7:52 ` Christoph Hellwig
2021-11-16 21:50 ` NeilBrown
2021-11-17 5:49 ` Christoph Hellwig
2021-11-16 2:44 ` [PATCH 08/13] NFS: discard NFS_RPC_SWAPFLAGS and RPC_TASK_ROOTCREDS NeilBrown
2021-11-16 2:44 ` [PATCH 01/13] NFS: move generic_write_checks() call from nfs_file_direct_write() to nfs_file_write() NeilBrown
2021-11-16 2:44 ` NeilBrown [this message]
2021-11-16 2:44 ` [PATCH 10/13] NFSv4: keep state manager thread active if swap is enabled NeilBrown
2021-11-16 2:44 ` [PATCH 05/13] SUNRPC/auth: async tasks mustn't block waiting for memory NeilBrown
2021-11-16 2:44 ` [PATCH 04/13] SUNRPC/call_alloc: " NeilBrown
2021-11-16 2:44 ` [PATCH 13/13] MM: use AIO for DIO writes to swap NeilBrown
2021-11-16 2:44 ` [PATCH 06/13] SUNRPC/xprt: async tasks mustn't block waiting for memory NeilBrown
2021-11-16 2:44 ` [PATCH 03/13] MM: reclaim mustn't enter FS for swap-over-NFS NeilBrown
2021-11-16 8:32 ` Christoph Hellwig
2021-11-16 21:35 ` NeilBrown
2021-11-17 5:50 ` Christoph Hellwig
2021-11-18 1:43 ` kernel test robot
2021-11-16 2:44 ` [PATCH 12/13] MM: use AIO/DIO for reads from SWP_FS_OPS swap-space NeilBrown
2021-11-16 8:31 ` Christoph Hellwig
2021-11-16 21:46 ` NeilBrown
2021-11-16 3:29 ` [PATCH 00/13] Repair SWAP-over-NFS Matthew Wilcox
2021-11-16 3:55 ` NeilBrown
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