From 5d02d33ee1e2143587e8b891af04eb56a228ab4d Mon Sep 17 00:00:00 2001
From: Olivier Houchard <ohouchard@haproxy.com>
Date: Mon, 2 Mar 2026 17:01:58 +0100
Subject: [PATCH] MINOR: stats: Add an option to disable the calculation of max
 counters

Add a new option, "stats calculate-max-counters [on|off]".
It makes it possible to disable the calculation of max counters, as they
can have a performance cost.
---
 doc/configuration.txt      |  5 +++++
 include/haproxy/counters.h |  4 +++-
 include/haproxy/global-t.h |  1 +
 src/cli.c                  | 12 +++++++++++-
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 7905e1815..a816666b6 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -3604,6 +3604,11 @@ ssl-skip-self-issued-ca
   certificates. It's useless for BoringSSL, .issuer is ignored because ocsp
   bits does not need it. Requires at least OpenSSL 1.0.2.
 
+stats calculate-max-counters [on|off]
+  Activates or deactivates the calculation of stats max counters. If you
+  don't need them, deactivating them may increase performances a bit.
+  The default is on.
+
 stats maxconn <connections>
   By default, the stats socket is limited to 10 concurrent connections. It is
   possible to change this value with "stats maxconn".
diff --git a/include/haproxy/counters.h b/include/haproxy/counters.h
index 6850e7b84..599b732ff 100644
--- a/include/haproxy/counters.h
+++ b/include/haproxy/counters.h
@@ -26,6 +26,7 @@
 
 #include <haproxy/counters-t.h>
 #include <haproxy/guid-t.h>
+#include <haproxy/global.h>
 
 extern THREAD_LOCAL void *trash_counters;
 
@@ -105,7 +106,8 @@ void counters_be_shared_drop(struct be_counters_shared *counters);
 
 #define COUNTERS_UPDATE_MAX(counter, count)                                   \
 	do {                                                                  \
-		HA_ATOMIC_UPDATE_MAX(counter, count);                         \
+		if (!(global.tune.options & GTUNE_NO_MAX_COUNTER))            \
+			HA_ATOMIC_UPDATE_MAX(counter, count);                 \
 	} while (0)
 
 /* Manipulation of extra_counters, for boot-time registrable modules */
diff --git a/include/haproxy/global-t.h b/include/haproxy/global-t.h
index 6b3ba5cd5..212b62bf7 100644
--- a/include/haproxy/global-t.h
+++ b/include/haproxy/global-t.h
@@ -86,6 +86,7 @@
 #define GTUNE_LISTENER_MQ_OPT    (1<<28)
 #define GTUNE_LISTENER_MQ_ANY    (GTUNE_LISTENER_MQ_FAIR | GTUNE_LISTENER_MQ_OPT)
 #define GTUNE_NO_KTLS            (1<<29)
+#define GTUNE_NO_MAX_COUNTER     (1<<30)
 
 /* subsystem-specific debugging options for tune.debug */
 #define GDBG_CPU_AFFINITY           (1U<< 0)
diff --git a/src/cli.c b/src/cli.c
index 312e2a2cb..55a514d09 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -616,12 +616,22 @@ static int cli_parse_global(char **args, int section_type, struct proxy *curpx,
 		}
 		global.cli_fe->maxconn = maxconn;
 	}
+	else if (strcmp(args[1], "calculate-max-counters") == 0) {
+		if (!strcasecmp(args[2], "on"))
+			return 0;
+		else if (!strcasecmp(args[2], "off")) {
+			global.tune.options |= GTUNE_NO_MAX_COUNTER;
+			return 0;
+		}
+		memprintf(err, "'%s' only supports 'on' and 'off', received '%s'", args[1], args[2]);
+		return -1;
+	}
 	else if (strcmp(args[1], "bind-process") == 0) {
 		memprintf(err, "'%s %s' is not supported anymore.", args[0], args[1]);
 		return -1;
 	}
 	else {
-		memprintf(err, "'%s' only supports 'socket', 'maxconn', 'bind-process' and 'timeout' (got '%s')", args[0], args[1]);
+		memprintf(err, "'%s' only supports 'socket', 'maxconn', 'bind-process', 'calculate-max-counters'  and 'timeout' (got '%s')", args[0], args[1]);
 		return -1;
 	}
 	return 0;