Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1276761170 -3600
# Node ID d0ad966b3d1a8653e2d147baf2843f2ca5ea7aed
# Parent 47655a695312af43c1dd163b22ab4adb02553f60
cpuidle: redirect some hpet lock users to a new cpumask_lock

The hpet channel lock was also used for prevent handle_hpet_broadcast
access other cpu's timer_deadline_start/end after other cpu was
already waken up.
This purpose can be approached via a standalone lock to remove much
spins on the hpet channel lock.

Signed-off-by: Wei Gang <gang.wei@intel.com>
---
xen/arch/x86/hpet.c | 11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)

diff -r 47655a695312 -r d0ad966b3d1a xen/arch/x86/hpet.c
--- a/xen/arch/x86/hpet.c Thu Jun 17 08:52:29 2010 +0100
+++ b/xen/arch/x86/hpet.c Thu Jun 17 08:52:50 2010 +0100
@@ -34,6 +34,7 @@ struct hpet_event_channel
int shift;
s_time_t next_event;
cpumask_t cpumask;
+ spinlock_t cpumask_lock;
spinlock_t lock;
void (*event_handler)(struct hpet_event_channel *);

@@ -196,7 +197,7 @@ again:
/* find all expired events */
for_each_cpu_mask(cpu, ch->cpumask)
{
- spin_lock_irq(&ch->lock);
+ spin_lock_irq(&ch->cpumask_lock);

if ( cpumask_test_cpu(cpu, ch->cpumask) )
{
@@ -206,7 +207,7 @@ again:
next_event = per_cpu(timer_deadline_end, cpu);
}

- spin_unlock_irq(&ch->lock);
+ spin_unlock_irq(&ch->cpumask_lock);
}

/* wakeup the cpus which have an expired event. */
@@ -579,6 +580,7 @@ void hpet_broadcast_init(void)
hpet_events[i].next_event = STIME_MAX;
hpet_events[i].event_handler = handle_hpet_broadcast;
spin_lock_init(&hpet_events[i].lock);
+ spin_lock_init(&hpet_events[i].cpumask_lock);
}

return;
@@ -613,6 +615,7 @@ void hpet_broadcast_init(void)
legacy_hpet_event.idx = 0;
legacy_hpet_event.flags = 0;
spin_lock_init(&legacy_hpet_event.lock);
+ spin_lock_init(&legacy_hpet_event.cpumask_lock);

if ( !force_hpet_broadcast )
pv_rtc_handler = handle_rtc_once;
@@ -689,9 +692,9 @@ void hpet_broadcast_exit(void)
if ( !reprogram_timer(this_cpu(timer_deadline_start)) )
raise_softirq(TIMER_SOFTIRQ);

- spin_lock_irq(&ch->lock);
+ spin_lock_irq(&ch->cpumask_lock);
cpu_clear(cpu, ch->cpumask);
- spin_unlock_irq(&ch->lock);
+ spin_unlock_irq(&ch->cpumask_lock);

if ( ch != &legacy_hpet_event )
{

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