---

yaml --- r: 53935 b: refs/heads/master c: c5bcb56 h: refs/heads/master i: 53933: 032357b 53931: 0fd0401 53927: 8c9a1e0 53919: b6b981b v: v3
git-mirror · May 2, 2007 · 4cd1de2 · 4cd1de2
1 parent cab01a3
commit 4cd1de2
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Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9bccb23dc5fc2d268ab676e2d4212d29e230fd86
+refs/heads/master: c5bcb5635a03da3158f121ae20ccbbf72b4fc62a
diff --git a/trunk/include/asm-i386/tsc.h b/trunk/include/asm-i386/tsc.h
@@ -37,6 +37,15 @@ static __always_inline cycles_t get_cycles_sync(void)
 	unsigned long long ret;
 	unsigned eax;
 
+	/*
+  	 * Use RDTSCP if possible; it is guaranteed to be synchronous
+ 	 * and doesn't cause a VMEXIT on Hypervisors
+	 */
+	alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP,
+			 	 "=A" (ret), "0" (0ULL) : "ecx", "memory");
+	if (ret)
+		return ret;
+
 	/*
 	 * Don't do an additional sync on CPUs where we know
 	 * RDTSC is already synchronous: