Re: [patch?] s2ram + P4 + tsc = annoyance

[Mike Galbraith]

Or, reset to pristine prior to testing, though that's more lines to
accomplish the same thing.  Either way, or some other way...

If check_tsc_warp() is called after initial boot, and the TSC has in the
meantime been set (BIOS, user, silicon, elves) to a value lower than the
last stored/stale value, we blame the TSC.  Reset to pristine condition
after every test.

Signed-off-by: Mike Galbraith <efault@xxxxxx>

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 9125efe..05d8f25 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -129,24 +129,24 @@ void __cpuinit check_tsc_sync_source(int cpu)
 	while (atomic_read(&stop_count) != cpus-1)
 		cpu_relax();
 
-	/*
-	 * Reset it - just in case we boot another CPU later:
-	 */
-	atomic_set(&start_count, 0);
-
 	if (nr_warps) {
 		printk("\n");
 		printk(KERN_WARNING "Measured %Ld cycles TSC warp between CPUs,"
 				    " turning off TSC clock.\n", max_warp);
 		mark_tsc_unstable("check_tsc_sync_source failed");
-		nr_warps = 0;
-		max_warp = 0;
-		last_tsc = 0;
 	} else {
 		printk(" passed.\n");
 	}
 
 	/*
+	 * Reset it - just in case we boot another CPU later:
+	 */
+	atomic_set(&start_count, 0);
+	nr_warps = 0;
+	max_warp = 0;
+	last_tsc = 0;
+
+	/*
 	 * Let the target continue with the bootup:
 	 */
 	atomic_inc(&stop_count);


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