[PATCH] synchronize_tsc() fixes

- Move the tsc synchronisation variables into a struct, mark it __initdata

- local `realdelta' wants to be 64-bit

- Print the skew for negative skews, as well as for positive ones

- remove dead code

Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 6f5fea05f1d7fc92a80e66819962cf4ee269086f..f948419c888a85905aa768f1aaeaf0c5378ca910 100644 (file)
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -212,14 +212,20 @@ valid_k7:
  * then we print a warning if not, and always resync.
  */
 
-static atomic_t tsc_start_flag = ATOMIC_INIT(0);
-static atomic_t tsc_count_start = ATOMIC_INIT(0);
-static atomic_t tsc_count_stop = ATOMIC_INIT(0);
-static unsigned long long tsc_values[NR_CPUS];
+static struct {
+       atomic_t start_flag;
+       atomic_t count_start;
+       atomic_t count_stop;
+       unsigned long long values[NR_CPUS];
+} tsc __initdata = {
+       .start_flag = ATOMIC_INIT(0),
+       .count_start = ATOMIC_INIT(0),
+       .count_stop = ATOMIC_INIT(0),
+};
 
 #define NR_LOOPS 5
 
-static void __init synchronize_tsc_bp (void)
+static void __init synchronize_tsc_bp(void)
 {
        int i;
        unsigned long long t0;
@@ -233,7 +239,7 @@ static void __init synchronize_tsc_bp (void)
        /* convert from kcyc/sec to cyc/usec */
        one_usec = cpu_khz / 1000;
 
-       atomic_set(&tsc_start_flag, 1);
+       atomic_set(&tsc.start_flag, 1);
        wmb();
 
        /*
@@ -250,16 +256,16 @@ static void __init synchronize_tsc_bp (void)
                /*
                 * all APs synchronize but they loop on '== num_cpus'
                 */
-               while (atomic_read(&tsc_count_start) != num_booting_cpus()-1)
+               while (atomic_read(&tsc.count_start) != num_booting_cpus()-1)
                        cpu_relax();
-               atomic_set(&tsc_count_stop, 0);
+               atomic_set(&tsc.count_stop, 0);
                wmb();
                /*
                 * this lets the APs save their current TSC:
                 */
-               atomic_inc(&tsc_count_start);
+               atomic_inc(&tsc.count_start);
 
-               rdtscll(tsc_values[smp_processor_id()]);
+               rdtscll(tsc.values[smp_processor_id()]);
                /*
                 * We clear the TSC in the last loop:
                 */
@@ -269,56 +275,54 @@ static void __init synchronize_tsc_bp (void)
                /*
                 * Wait for all APs to leave the synchronization point:
                 */
-               while (atomic_read(&tsc_count_stop) != num_booting_cpus()-1)
+               while (atomic_read(&tsc.count_stop) != num_booting_cpus()-1)
                        cpu_relax();
-               atomic_set(&tsc_count_start, 0);
+               atomic_set(&tsc.count_start, 0);
                wmb();
-               atomic_inc(&tsc_count_stop);
+               atomic_inc(&tsc.count_stop);
        }
 
        sum = 0;
        for (i = 0; i < NR_CPUS; i++) {
                if (cpu_isset(i, cpu_callout_map)) {
-                       t0 = tsc_values[i];
+                       t0 = tsc.values[i];
                        sum += t0;
                }
        }
        avg = sum;
        do_div(avg, num_booting_cpus());
 
-       sum = 0;
        for (i = 0; i < NR_CPUS; i++) {
                if (!cpu_isset(i, cpu_callout_map))
                        continue;
-               delta = tsc_values[i] - avg;
+               delta = tsc.values[i] - avg;
                if (delta < 0)
                        delta = -delta;
                /*
                 * We report bigger than 2 microseconds clock differences.
                 */
                if (delta > 2*one_usec) {
-                       long realdelta;
+                       long long realdelta;
+
                        if (!buggy) {
                                buggy = 1;
                                printk("\n");
                        }
                        realdelta = delta;
                        do_div(realdelta, one_usec);
-                       if (tsc_values[i] < avg)
+                       if (tsc.values[i] < avg)
                                realdelta = -realdelta;
 
-                       if (realdelta > 0)
-                               printk(KERN_INFO "CPU#%d had %ld usecs TSC "
+                       if (realdelta)
+                               printk(KERN_INFO "CPU#%d had %Ld usecs TSC "
                                        "skew, fixed it up.\n", i, realdelta);
                }
-
-               sum += delta;
        }
        if (!buggy)
                printk("passed.\n");
 }
 
-static void __init synchronize_tsc_ap (void)
+static void __init synchronize_tsc_ap(void)
 {
        int i;
 
@@ -327,20 +331,20 @@ static void __init synchronize_tsc_ap (void)
         * this gets called, so we first wait for the BP to
         * finish SMP initialization:
         */
-       while (!atomic_read(&tsc_start_flag))
+       while (!atomic_read(&tsc.start_flag))
                cpu_relax();
 
        for (i = 0; i < NR_LOOPS; i++) {
-               atomic_inc(&tsc_count_start);
-               while (atomic_read(&tsc_count_start) != num_booting_cpus())
+               atomic_inc(&tsc.count_start);
+               while (atomic_read(&tsc.count_start) != num_booting_cpus())
                        cpu_relax();
 
-               rdtscll(tsc_values[smp_processor_id()]);
+               rdtscll(tsc.values[smp_processor_id()]);
                if (i == NR_LOOPS-1)
                        write_tsc(0, 0);
 
-               atomic_inc(&tsc_count_stop);
-               while (atomic_read(&tsc_count_stop) != num_booting_cpus())
+               atomic_inc(&tsc.count_stop);
+               while (atomic_read(&tsc.count_stop) != num_booting_cpus())
                        cpu_relax();
        }
 }