diff options
| author | Steven Rostedt <srostedt@redhat.com> | 2009-09-15 12:24:22 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2009-09-15 12:24:22 -0400 |
| commit | 6ca6cca31ddc7cc8b1dc38b12d7593d2667defe8 (patch) | |
| tree | ca29469e6f270d9c9a85ac77c41658ebbfd8f99f /kernel/trace | |
| parent | 555f386c98cc93890f48fdea098936755270304b (diff) | |
tracing: optimize global_trace_clock cachelines
The prev_trace_clock_time is only read or written to when the
trace_clock_lock is taken. For better perfomance, they
should share the same cache line.
Reported-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace_clock.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c index b588fd81f7f..20c5f92e28a 100644 --- a/kernel/trace/trace_clock.c +++ b/kernel/trace/trace_clock.c @@ -66,10 +66,14 @@ u64 notrace trace_clock(void) * Used by plugins that need globally coherent timestamps. */ -static u64 prev_trace_clock_time; - -static raw_spinlock_t trace_clock_lock ____cacheline_aligned_in_smp = - (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; +/* keep prev_time and lock in the same cacheline. */ +static struct { + u64 prev_time; + raw_spinlock_t lock; +} trace_clock_struct ____cacheline_aligned_in_smp = + { + .lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED, + }; u64 notrace trace_clock_global(void) { @@ -88,19 +92,19 @@ u64 notrace trace_clock_global(void) if (unlikely(in_nmi())) goto out; - __raw_spin_lock(&trace_clock_lock); + __raw_spin_lock(&trace_clock_struct.lock); /* * TODO: if this happens often then maybe we should reset - * my_scd->clock to prev_trace_clock_time+1, to make sure + * my_scd->clock to prev_time+1, to make sure * we start ticking with the local clock from now on? */ - if ((s64)(now - prev_trace_clock_time) < 0) - now = prev_trace_clock_time + 1; + if ((s64)(now - trace_clock_struct.prev_time) < 0) + now = trace_clock_struct.prev_time + 1; - prev_trace_clock_time = now; + trace_clock_struct.prev_time = now; - __raw_spin_unlock(&trace_clock_lock); + __raw_spin_unlock(&trace_clock_struct.lock); out: raw_local_irq_restore(flags); |