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authorAndreas Mohr <andi@rhlx01.fht-esslingen.de>2006-06-25 05:46:52 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-25 10:00:55 -0700
commit186989177e627c2571a3026d39ea1433e4ddc097 (patch)
treefacbda2b471468dfc3b483c6711094e8495e0eec
parente75eac33b5c7f797e4b2ddcb39183cf268e26822 (diff)
[PATCH] cpu_relax(): smpboot.c
Add cpu_relax() to various smpboot.c init loops. cpu_relax() always implies a barrier (according to Arjan), so remove those as well. Signed-off-by: Andreas Mohr <andi@lisas.de> Cc: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/smpboot.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 825b2b4ca721..bd0ca5c9f053 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -257,7 +257,7 @@ 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)
- mb();
+ cpu_relax();
atomic_set(&tsc_count_stop, 0);
wmb();
/*
@@ -276,7 +276,7 @@ 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)
- mb();
+ cpu_relax();
atomic_set(&tsc_count_start, 0);
wmb();
atomic_inc(&tsc_count_stop);
@@ -333,19 +333,21 @@ 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)) mb();
+ 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())
- mb();
+ cpu_relax();
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()) mb();
+ while (atomic_read(&tsc_count_stop) != num_booting_cpus())
+ cpu_relax();
}
}
#undef NR_LOOPS
@@ -1433,7 +1435,7 @@ int __devinit __cpu_up(unsigned int cpu)
/* Unleash the CPU! */
cpu_set(cpu, smp_commenced_mask);
while (!cpu_isset(cpu, cpu_online_map))
- mb();
+ cpu_relax();
return 0;
}