File sysstat-compute-global-CPU-stats-2.patch of Package sysstat.7878

From 9057b41fcbf509a6dd2cefe8be31c7181e3c905c Mon Sep 17 00:00:00 2001
From: Sebastien GODARD <sysstat@users.noreply.github.com>
Date: Sat, 10 Mar 2018 15:08:49 +0100
Subject: [PATCH] Change condition used in workaround for CPU coming back
 online

Compare counter's value to ULLONG_MAX - 0x7ffff (and not ULLONG_MAX &
0x80000) to guess if it has overflown.

Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>
---
 rd_stats.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Index: sysstat-10.2.1/common.c
===================================================================
--- sysstat-10.2.1.orig/common.c	2014-01-19 10:01:01.000000000 +0000
+++ sysstat-10.2.1/common.c	2018-06-20 10:29:26.722239561 +0000
@@ -22,6 +22,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <limits.h>
 #include <time.h>
 #include <errno.h>
 #include <unistd.h>	/* For STDOUT_FILENO, among others */
@@ -601,6 +602,24 @@ unsigned long long get_per_cpu_interval(
 	}
 	
 	/*
+	 * Workaround for CPU coming back online: With recent kernels
+	 * some fields (user, nice, system) restart from their previous value,
+	 * whereas others (idle, iowait) restart from zero.
+	 * For the latter we need to set their previous value to zero to
+	 * avoid getting an interval value < 0.
+	 * (I don't know how the other fields like hardirq, steal... behave).
+	 * Don't assume the CPU has come back from offline state if previous
+	 * value was greater than ULLONG_MAX - 0x7ffff (the counter probably
+	 * overflew).
+	 */
+	if ((scc->cpu_idle < scp->cpu_idle) && (scp->cpu_idle < (ULLONG_MAX - 0x7ffff))) {
+		scp->cpu_idle = 0;
+	}
+	if ((scc->cpu_iowait < scp->cpu_iowait) && (scp->cpu_iowait < (ULLONG_MAX - 0x7ffff))) {
+		scp->cpu_iowait = 0;
+	}
+
+	/*
 	 * Don't take cpu_guest and cpu_guest_nice into account
 	 * because cpu_user and cpu_nice already include them.
 	 */