linux-kernel - [PATCH 3/3] net: better handling for network busy poll

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Message-Id: <20201023032944.399861-3-joshdon@google.com>
Date:   Thu, 22 Oct 2020 20:29:44 -0700
From:   Josh Don <joshdon@...gle.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        kvm@...r.kernel.org, Josh Don <joshdon@...gle.com>,
        Xi Wang <xii@...gle.com>
Subject: [PATCH 3/3] net: better handling for network busy poll

Add the new functions prepare_to_busy_poll() and friends to
napi_busy_loop(). The busy polling cpu will be considered an idle
target during wake up balancing.

Suggested-by: Xi Wang <xii@...gle.com>
Signed-off-by: Josh Don <joshdon@...gle.com>
Signed-off-by: Xi Wang <xii@...gle.com>
---
 net/core/dev.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 266073e300b5..4fb4ae4b27fc 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6476,7 +6476,7 @@ void napi_busy_loop(unsigned int napi_id,
 	if (!napi)
 		goto out;
 
-	preempt_disable();
+	prepare_to_busy_poll(); /* disables preemption */
 	for (;;) {
 		int work = 0;
 
@@ -6509,10 +6509,10 @@ void napi_busy_loop(unsigned int napi_id,
 		if (!loop_end || loop_end(loop_end_arg, start_time))
 			break;
 
-		if (unlikely(need_resched())) {
+		if (unlikely(!continue_busy_poll())) {
 			if (napi_poll)
 				busy_poll_stop(napi, have_poll_lock);
-			preempt_enable();
+			end_busy_poll(true);
 			rcu_read_unlock();
 			cond_resched();
 			if (loop_end(loop_end_arg, start_time))
@@ -6523,7 +6523,7 @@ void napi_busy_loop(unsigned int napi_id,
 	}
 	if (napi_poll)
 		busy_poll_stop(napi, have_poll_lock);
-	preempt_enable();
+	end_busy_poll(true);
 out:
 	rcu_read_unlock();
 }
-- 
2.29.0.rc1.297.gfa9743e501-goog