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authorAndrew Morton <akpm@osdl.org>2006-07-30 03:03:19 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-31 13:28:38 -0700
commitc35a7261eaf0e57924e2c56c6d72dc44ee9f3634 (patch)
treecb59f2b3ca4b7705ee715824d0e8aeb37454de57 /arch
parent851f8a6906b71f7a19043d4d722dd4ffab7aeafc (diff)
[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>
Diffstat (limited to 'arch')
-rw-r--r--arch/i386/kernel/smpboot.c62
1 files changed, 33 insertions, 29 deletions
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 6f5fea05f1d7..f948419c888a 100644
--- 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();
}
}