From a70042067180b4fa068909a2bff48227bb8e3c98 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Wed, 21 Sep 2022 07:37:27 +0200
Subject: [PATCH] MINOR: clock: split local and global date updates

Pollers that support busy polling spend a lot of time (and cause
contention) updating the global date when they're looping over themselves
while it serves no purpose: what's needed is only an update on the local
date to know when to stop looping.

This patch splits clock_pudate_date() into a pair of local and global
update functions, so that pollers can be easily improved.
---
 include/haproxy/clock.h |  9 ++++++++-
 src/clock.c             | 23 ++++++++++++++++-------
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/include/haproxy/clock.h b/include/haproxy/clock.h
index dedcacb24..22bb2c947 100644
--- a/include/haproxy/clock.h
+++ b/include/haproxy/clock.h
@@ -35,7 +35,8 @@ uint64_t now_cpu_time_thread(int thr);
 uint64_t now_mono_time(void);
 uint64_t now_cpu_time(void);
 void clock_set_local_source(void);
-void clock_update_date(int max_wait, int interrupted);
+void clock_update_local_date(int max_wait, int interrupted);
+void clock_update_global_date();
 void clock_init_process_date(void);
 void clock_init_thread_date(void);
 int clock_setup_signal_timer(void *timer, int sig, int val);
@@ -44,4 +45,10 @@ uint clock_report_idle(void);
 void clock_leaving_poll(int timeout, int interrupted);
 void clock_entering_poll(void);
 
+static inline void clock_update_date(int max_wait, int interrupted)
+{
+	clock_update_local_date(max_wait, interrupted);
+	clock_update_global_date();
+}
+
 #endif
diff --git a/src/clock.c b/src/clock.c
index 099057f7d..c00243faf 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -147,14 +147,10 @@ int clock_setup_signal_timer(void *tmr, int sig, int val)
  * values for the tv_sec and tv_usec parts. The offset is made of two signed
  * ints so that the clock can be adjusted in the two directions.
  */
-void clock_update_date(int max_wait, int interrupted)
+void clock_update_local_date(int max_wait, int interrupted)
 {
-	struct timeval min_deadline, max_deadline, tmp_now;
-	uint old_now_ms;
-	ullong old_now;
-	ullong new_now;
-	ullong ofs, ofs_new;
-	uint sec_ofs, usec_ofs;
+	struct timeval min_deadline, max_deadline;
+	ullong ofs;
 
 	gettimeofday(&date, NULL);
 
@@ -194,6 +190,19 @@ void clock_update_date(int max_wait, int interrupted)
 			now.tv_sec  += 1;
 		}
 	}
+	now_ms = __tv_to_ms(&now);
+}
+
+void clock_update_global_date()
+{
+	struct timeval tmp_now;
+	uint old_now_ms;
+	ullong old_now;
+	ullong new_now;
+	ullong ofs, ofs_new;
+	uint sec_ofs, usec_ofs;
+
+	ofs = HA_ATOMIC_LOAD(&now_offset);
 
 	/* now that we have bounded the local time, let's check if it's
 	 * realistic regarding the global date, which only moves forward,