linux-kernel - [PATCH 1/7] turbostat: set max_num_cpus equal to the cpumask length

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Date:   Sun, 16 Jul 2017 16:49:57 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     nhorman@...hat.com, Prarit Bhargava <prarit@...hat.com>,
        Len Brown <len.brown@...el.com>
Subject: [PATCH 1/7] turbostat: set max_num_cpus equal to the cpumask length

Future fixes will use sysfs files that contain cpumask output.  The code
needs to know the length of the cpumask in order to determine which cpus
are set in a cpumask.  Currently topo.max_cpu_num is the maximum cpu
number.  It can be increased the the maximum value of cpus represented in
cpumasks.

Set max_num_cpus to the length of a cpumask.

Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Len Brown <len.brown@...el.com>
---
 tools/power/x86/turbostat/turbostat.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 0dafba2c1e7d..6d368e744d27 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -2413,6 +2413,20 @@ void re_initialize(void)
 	printf("turbostat: re-initialized with num_cpus %d\n", topo.num_cpus);
 }
 
+void set_max_cpu_num(void)
+{
+	FILE *filep;
+	unsigned long dummy;
+
+	topo.max_cpu_num = 0;
+	filep = fopen_or_die(
+			"/sys/devices/system/cpu/cpu0/topology/thread_siblings",
+			"r");
+	while (fscanf(filep, "%lx,", &dummy) == 1)
+		topo.max_cpu_num+=32;
+	fclose(filep);
+	topo.max_cpu_num--; /* 0 based */
+}
 
 /*
  * count_cpus()
@@ -2420,10 +2434,7 @@ void re_initialize(void)
  */
 int count_cpus(int cpu)
 {
-	if (topo.max_cpu_num < cpu)
-		topo.max_cpu_num = cpu;
-
-	topo.num_cpus += 1;
+	topo.num_cpus++;
 	return 0;
 }
 int mark_cpu_present(int cpu)
@@ -4320,8 +4331,8 @@ void topology_probe()
 	} *cpus;
 
 	/* Initialize num_cpus, max_cpu_num */
+	set_max_cpu_num();
 	topo.num_cpus = 0;
-	topo.max_cpu_num = 0;
 	for_all_proc_cpus(count_cpus);
 	if (!summary_only && topo.num_cpus > 1)
 		BIC_PRESENT(BIC_CPU);
-- 
1.8.5.5