From: Jim Harris <james.r.harris@intel.com>
Date: Mon, 7 Oct 2019 15:40:05 +0000 (-0700)
Subject: timer: remove useless check on x86 TSC reliability
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=c1077933d45b2bb6b8721746e63f5a125bd2353a;p=dpdk.git

timer: remove useless check on x86 TSC reliability

This code was added 7+ years ago in
commit fb022b85bae4 ("timer: check TSC reliability")
presumably when variant TSCs were still somewhat common.

But this code doesn't do anything except print a warning,
and the warning doesn't give any kind of advice to the user,
so let's just remove it.

While the warning has no functional meaning, the /proc/cpuinfo
parsing consumes a non-trivial amount of time which is especially
noticeable in secondary processes.
On my test system, it consumes 21ms out of the 66ms total execution
time for rte_eal_init() in a secondary process.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---

diff --git a/lib/librte_eal/linux/eal/eal_timer.c b/lib/librte_eal/linux/eal/eal_timer.c
index 76ec17034b..a904a8297c 100644
--- a/lib/librte_eal/linux/eal/eal_timer.c
+++ b/lib/librte_eal/linux/eal/eal_timer.c
@@ -192,41 +192,6 @@ 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);
-}
-
 uint64_t
 get_tsc_freq(void)
 {
@@ -263,6 +228,5 @@ rte_eal_timer_init(void)
 	eal_timer_source = EAL_TIMER_TSC;
 
 	set_tsc_freq();
-	check_tsc_flags();
 	return 0;
 }