From c415c77ea8069e4e4468b2b9a6a31769f47dcba7 Mon Sep 17 00:00:00 2001
From: Sepherosa Ziehau <sephe@dragonflybsd.org>
Date: Wed, 19 Jun 2013 16:54:41 +0800
Subject: [PATCH] net: Use tsc_invariant when it is necessary; mainly in time
 measure

---
 sys/net/altq/altq_subr.c | 10 +++++++---
 sys/net/if_poll.c        |  2 +-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/sys/net/altq/altq_subr.c b/sys/net/altq/altq_subr.c
index 9f58bd7660..87558dd8a9 100644
--- a/sys/net/altq/altq_subr.c
+++ b/sys/net/altq/altq_subr.c
@@ -809,9 +809,10 @@ init_machclk(void)
 #endif
 
 #if defined(__i386__) || defined(__x86_64__)
-	/* check if TSC is available */
-	if ((cpu_feature & CPUID_TSC) == 0)
+	if (!tsc_present) {
+		/* No TSC */
 		machclk_usepcc = 0;
+	}
 
 	if (ncpus > 1) {
 		/*
@@ -821,6 +822,9 @@ init_machclk(void)
 		 * across CPUs or not.
 		 */
 		machclk_usepcc = 0;
+	} else if (!tsc_invariant) {
+		/* Not invariant TSC */
+		machclk_usepcc = 0;
 	}
 #else
 	machclk_usepcc = 0;
@@ -842,7 +846,7 @@ init_machclk(void)
 	 * just use it.
 	 */
 #ifdef _RDTSC_SUPPORTED_
-	if (cpu_feature & CPUID_TSC)
+	if (tsc_present)
 		machclk_freq = (uint64_t)tsc_frequency;
 #endif
 
diff --git a/sys/net/if_poll.c b/sys/net/if_poll.c
index bfb1b0feff..ffe84b5a29 100644
--- a/sys/net/if_poll.c
+++ b/sys/net/if_poll.c
@@ -316,7 +316,7 @@ sched_iopollmore(struct iopoll_ctx *io_ctx)
 static __inline void
 ifpoll_time_get(union ifpoll_time *t)
 {
-	if (__predict_true(tsc_present))
+	if (tsc_invariant)
 		t->tsc = rdtsc();
 	else
 		microuptime(&t->tv);
-- 
2.41.0