x86: Limit number of per cpu TSC sync messages

Limit the number of per cpu TSC sync messages by only printing
to the console if an error occurs, otherwise print as a DEBUG
message.

The info message "Skipping synchronization ..." is only printed
after the last cpu has booted.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091118002222.181053000@alcatraz.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index f379309..eed1568 100644 (file)
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -114,13 +114,12 @@ void __cpuinit check_tsc_sync_source(int cpu)
                return;
 
        if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) {
-               printk_once(KERN_INFO "Skipping synchronization checks as TSC is reliable.\n");
+               if (cpu == (nr_cpu_ids-1) || system_state != SYSTEM_BOOTING)
+                       pr_info(
+                       "Skipped synchronization checks as TSC is reliable.\n");
                return;
        }
 
-       pr_info("checking TSC synchronization [CPU#%d -> CPU#%d]:",
-               smp_processor_id(), cpu);
-
        /*
         * Reset it - in case this is a second bootup:
         */
@@ -142,12 +141,14 @@ void __cpuinit check_tsc_sync_source(int cpu)
                cpu_relax();
 
        if (nr_warps) {
-               printk("\n");
+               pr_warning("TSC synchronization [CPU#%d -> CPU#%d]:\n",
+                       smp_processor_id(), cpu);
                pr_warning("Measured %Ld cycles TSC warp between CPUs, "
                           "turning off TSC clock.\n", max_warp);
                mark_tsc_unstable("check_tsc_sync_source failed");
        } else {
-               printk(" passed.\n");
+               pr_debug("TSC synchronization [CPU#%d -> CPU#%d]: passed\n",
+                       smp_processor_id(), cpu);
        }
 
        /*