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[v2,5/5] SUNRPC: Optimize page release in svc_rdma_sendto()

Message ID 168657902707.5619.1368921836287929972.stgit@manet.1015granger.net (mailing list archive)
State Not Applicable
Headers show
Series svcrdma: Go back to releasing pages-under-I/O | expand

Commit Message

Chuck Lever June 12, 2023, 2:10 p.m. UTC 
From: Chuck Lever <chuck.lever@oracle.com>

Now that we have bulk page allocation and release APIs, it's more
efficient to use those than it is for nfsd threads to wait for send
completions. Previous patches have eliminated the calls to
wait_for_completion() and complete(), in order to avoid scheduler
overhead.

Now release pages-under-I/O in the send completion handler using
the efficient bulk release API.

I've measured a 7% reduction in cumulative CPU utilization in
svc_rdma_sendto(), svc_rdma_wc_send(), and svc_xprt_release(). In
particular, using release_pages() instead of complete() cuts the
time per svc_rdma_wc_send() call by two-thirds. This helps improve
scalability because svc_rdma_wc_send() is single-threaded per
connection.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Tom Talpey <tom@talpey.com>
---
 net/sunrpc/xprtrdma/svc_rdma_sendto.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index 1ae4236d04a3..24228f3611e8 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -236,8 +236,8 @@  void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma,
 	struct ib_device *device = rdma->sc_cm_id->device;
 	unsigned int i;
 
-	for (i = 0; i < ctxt->sc_page_count; ++i)
-		put_page(ctxt->sc_pages[i]);
+	if (ctxt->sc_page_count)
+		release_pages(ctxt->sc_pages, ctxt->sc_page_count);
 
 	/* The first SGE contains the transport header, which
 	 * remains mapped until @ctxt is destroyed.