From: Ivan Boule <ivan.boule@6wind.com>
Date: Thu, 31 May 2012 14:41:57 +0000 (+0200)
Subject: timer: check TSC reliability
X-Git-Tag: spdx-start~10956
X-Git-Url: http://git.droids-corp.org/?p=dpdk.git;a=commitdiff_plain;h=fb022b85bae4e262922a3ab035adadb03c57387e

timer: check TSC reliability

Read flags from /proc/cpuinfo and warn if constant_tsc or nonstop_tsc is
not found.

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
Acked-by: Ivan Boule <ivan.boule@6wind.com>
---

diff --git a/lib/librte_eal/linuxapp/eal/eal_timer.c b/lib/librte_eal/linuxapp/eal/eal_timer.c
index b6cea1790d..64566d143d 100644
--- a/lib/librte_eal/linuxapp/eal/eal_timer.c
+++ b/lib/librte_eal/linuxapp/eal/eal_timer.c
@@ -2,6 +2,7 @@
  *   BSD LICENSE
  * 
  *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+ *   Copyright(c) 2012-2013 6WIND S.A.
  *   All rights reserved.
  * 
  *   Redistribution and use in source and binary forms, with or without
@@ -242,6 +243,41 @@ rte_eal_hpet_init(int make_default)
 }
 #endif
 
+static void
+check_tsc_flags(void)
+{
+	char line[512];
+	FILE *stream;
+
+	stream = fopen("/proc/cpuinfo", "r");
+	if (!stream) {
+		RTE_LOG(WARNING, EAL, "WARNING: Unable to open /proc/cpuinfo\n");
+		return;
+	}
+
+	while (fgets(line, sizeof line, stream)) {
+		char *constant_tsc;
+		char *nonstop_tsc;
+
+		if (strncmp(line, "flags", 5) != 0)
+			continue;
+
+		constant_tsc = strstr(line, "constant_tsc");
+		nonstop_tsc = strstr(line, "nonstop_tsc");
+		if (!constant_tsc || !nonstop_tsc)
+			RTE_LOG(WARNING, EAL,
+				"WARNING: cpu flags "
+				"constant_tsc=%s "
+				"nonstop_tsc=%s "
+				"-> using unreliable clock cycles !\n",
+				constant_tsc ? "yes":"no",
+				nonstop_tsc ? "yes":"no");
+		break;
+	}
+
+	fclose(stream);
+}
+
 static int
 set_tsc_freq_from_clock(void)
 {
@@ -304,5 +340,6 @@ rte_eal_timer_init(void)
 	eal_timer_source = EAL_TIMER_TSC;
 
 	set_tsc_freq();
+	check_tsc_flags();
 	return 0;
 }