On Nov 7, 2022, at 10:55 AM, Jeff Layton [off-list ref] wrote:

On Mon, 2022-11-07 at 15:11 +0000, Chuck Lever III wrote:

quoted

Hi Jeff -

quoted

On Nov 7, 2022, at 10:01 AM, Jeff Layton [off-list ref] wrote:

nfsd has grown a dedicated workqueue for the filecache, but this job is
still queued to the system_wq. Change it to use the filecache_wq.

Actually... there doesn't seem to be anything special about
nfsd_filecache_wq. 9542e6a643fc ("nfsd: Containerise filecache
laundrette") does not make clear why it was added.

Playing devil's advocate: why not make the converse change and
replace it with system_wq?

Good question.

At one time, allocating a workqueue gave you a dedicated pool of
threads, but that's no longer the case.

Documentation/core-api/workqueue.rst says: "A wq no longer manages
execution resources but serves as a domain for forward progress
guarantee, flush and work item attributes."

Given that we're allocating this workqueue exactly the same way we
allocate the system_wq, I don't think we need our own workqueue at all.
I'd be fine with changing this to be the reverse if you prefer.

One less thing to fail on module initialization. Go for it.

quoted

quoted

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nfsd/filecache.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 1e76b0d3b83a..018fd1565193 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c

@@ -212,7 +212,7 @@ static void

nfsd_file_schedule_laundrette(void)
{
	if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags))
-		queue_delayed_work(system_wq, &nfsd_filecache_laundrette,
+		queue_delayed_work(nfsd_filecache_wq, &nfsd_filecache_laundrette,
				   NFSD_LAUNDRETTE_DELAY);
}

-- 
2.38.1

--
Chuck Lever

-- 
Jeff Layton [off-list ref]

--
Chuck Lever