From ec61263b9c0e8bd4ecab8d7636cd50da62286464 Mon Sep 17 00:00:00 2001 From: "kaf24@firebug.cl.cam.ac.uk" Date: Mon, 30 May 2005 10:35:55 +0000 Subject: [PATCH] bitkeeper revision 1.1593 (429aec8bP8S_iGAVT8JuCkjdgPLCCg) Manual update for rcu changes in 2.0-testing. Signed-off-by: Keir Fraser --- .../arch/xen/i386/kernel/time.c | 76 +++++++++---------- 1 file changed, 35 insertions(+), 41 deletions(-) diff --git a/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c b/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c index f7f20487e6..821d6905b0 100644 --- a/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c +++ b/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c @@ -689,58 +689,52 @@ void __init time_init(void) (void)setup_irq(per_cpu(timer_irq, 0), &irq_timer); } -/* Convert jiffies to system time. Call with xtime_lock held for reading. */ -static inline u64 __jiffies_to_st(unsigned long j) +/* Convert jiffies to system time. */ +static inline u64 jiffies_to_st(unsigned long j) { - long delta = j - jiffies; - /* NB. The next check can trigger in some wrap-around cases, but - * that's ok -- we'll just end up with a shorter timeout. */ - if (delta < 1) - delta = 1; - return processed_system_time + (delta * NS_PER_TICK); + unsigned long seq; + long delta; + u64 st; + + do { + seq = read_seqbegin(&xtime_lock); + delta = j - jiffies; + /* NB. The next check can trigger in some wrap-around cases, + * but that's ok: we'll just end up with a shorter timeout. */ + if (delta < 1) + delta = 1; + st = processed_system_time + (delta * NS_PER_TICK); + } while (read_seqretry(&xtime_lock, seq)); + + return st; } /* - * This function works out when the the next timer function has to be - * executed (by looking at the timer list) and sets the Xen one-shot - * domain timer to the appropriate value. This is typically called in - * cpu_idle() before the domain blocks. - * - * The function returns a non-0 value on error conditions. - * - * It must be called with interrupts disabled. + * stop_hz_timer / start_hz_timer - enter/exit 'tickless mode' on an idle cpu + * These functions are based on implementations from arch/s390/kernel/time.c */ -int set_timeout_timer(void) +void stop_hz_timer(void) { - u64 alarm = 0; - int ret = 0; + unsigned int cpu = smp_processor_id(); unsigned long j; -#ifdef CONFIG_SMP - unsigned long seq; -#endif - /* - * This is safe against long blocking (since calculations are - * not based on TSC deltas). It is also safe against warped - * system time since suspend-resume is cooperative and we - * would first get locked out. - */ -#ifdef CONFIG_SMP - do { - seq = read_seqbegin(&xtime_lock); + /* s390 does this /before/ checking rcu_pending(). We copy them. */ + cpu_set(cpu, nohz_cpu_mask); + + /* Leave ourselves in 'tick mode' if rcu or softirq pending. */ + if (rcu_pending(cpu) || local_softirq_pending()) { + cpu_clear(cpu, nohz_cpu_mask); j = jiffies + 1; - alarm = __jiffies_to_st(j); - } while (read_seqretry(&xtime_lock, seq)); -#else - j = next_timer_interrupt(); - alarm = __jiffies_to_st(j); -#endif + } else { + j = next_timer_interrupt(); + } - /* Failure is pretty bad, but we'd best soldier on. */ - if ( HYPERVISOR_set_timer_op(alarm) != 0 ) - ret = -1; + BUG_ON(HYPERVISOR_set_timer_op(jiffies_to_st(j)) != 0); +} - return ret; +void start_hz_timer(void) +{ + cpu_clear(smp_processor_id(), nohz_cpu_mask); } void time_suspend(void) -- 2.30.2