From 820de5c39ef7f6866d2c9e6c7d208bcd2a6e1942 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sat, 21 Jul 2007 04:37:36 -0700 Subject: highres: improve debug output Add some more debug information to the hrtimer and clock events code. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Cc: john stultz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/hrtimer.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/hrtimer.c') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 72d034258ba1..065a89786628 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -558,7 +558,8 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer, */ static int hrtimer_switch_to_hres(void) { - struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases); + int cpu = smp_processor_id(); + struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu); unsigned long flags; if (base->hres_active) @@ -568,6 +569,8 @@ static int hrtimer_switch_to_hres(void) if (tick_init_highres()) { local_irq_restore(flags); + printk(KERN_WARNING "Could not switch to high resolution " + "mode on CPU %d\n", cpu); return 0; } base->hres_active = 1; -- cgit v1.2.3 From 99bc2fcb283852931fb6bbef40f3df8316b59000 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sat, 21 Jul 2007 04:37:36 -0700 Subject: hrtimer: speedup hrtimer_enqueue Speedup hrtimer_enqueue by evaluating the rbtree insertion result. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Cc: john stultz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/hrtimer.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel/hrtimer.c') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 065a89786628..eb1ddebd2c04 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -686,6 +686,7 @@ static void enqueue_hrtimer(struct hrtimer *timer, struct rb_node **link = &base->active.rb_node; struct rb_node *parent = NULL; struct hrtimer *entry; + int leftmost = 1; /* * Find the right place in the rbtree: @@ -697,18 +698,19 @@ static void enqueue_hrtimer(struct hrtimer *timer, * We dont care about collisions. Nodes with * the same expiry time stay together. */ - if (timer->expires.tv64 < entry->expires.tv64) + if (timer->expires.tv64 < entry->expires.tv64) { link = &(*link)->rb_left; - else + } else { link = &(*link)->rb_right; + leftmost = 0; + } } /* * Insert the timer to the rbtree and check whether it * replaces the first pending timer */ - if (!base->first || timer->expires.tv64 < - rb_entry(base->first, struct hrtimer, node)->expires.tv64) { + if (leftmost) { /* * Reprogram the clock event device. When the timer is already * expired hrtimer_enqueue_reprogram has either called the -- cgit v1.2.3 From 2c6b47de17c75d553de3e2fb426d8298d2074585 Mon Sep 17 00:00:00 2001 From: john stultz Date: Tue, 24 Jul 2007 17:47:43 -0700 Subject: Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time(). This avoids use of the kernel-internal "xtime" variable directly outside of the actual time-related functions. Instead, use the helper functions that we already have available to us. This doesn't actually change any behaviour, but this will allow us to fix the fact that "xtime" isn't updated very often with CONFIG_NO_HZ (because much of the realtime information is maintained as separate offsets to 'xtime'), which has caused interfaces that use xtime directly to get a time that is out of sync with the real-time clock by up to a third of a second or so. Signed-off-by: John Stultz Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Linus Torvalds --- kernel/hrtimer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/hrtimer.c') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index eb1ddebd2c04..a7bb05e6cb63 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -144,7 +144,7 @@ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base) #ifdef CONFIG_NO_HZ getnstimeofday(&xts); #else - xts = xtime; + xts = current_kernel_time(); #endif tom = wall_to_monotonic; } while (read_seqretry(&xtime_lock, seq)); -- cgit v1.2.3 From 17c38b7490b3f0300c7812aefdae2ddda7ab4112 Mon Sep 17 00:00:00 2001 From: john stultz Date: Tue, 24 Jul 2007 18:38:34 -0700 Subject: Cache xtime every call to update_wall_time This avoids xtime lag seen with dynticks, because while 'xtime' itself is still not updated often, we keep a 'xtime_cache' variable around that contains the approximate real-time that _is_ updated each time we do a 'update_wall_time()', and is thus never off by more than one tick. IOW, this restores the original semantics for 'xtime' users, as long as you use the proper abstraction functions (ie 'current_kernel_time()' or 'get_seconds()' depending on whether you want a timespec or just the seconds field). [ Updated Patch. As penance for my sins I've also yanked another #ifdef that was added to avoid the xtime lag w/ hrtimers. ] Signed-off-by: John Stultz Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Linus Torvalds --- kernel/hrtimer.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'kernel/hrtimer.c') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index a7bb05e6cb63..c21ca6bfaa66 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -141,11 +141,7 @@ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base) do { seq = read_seqbegin(&xtime_lock); -#ifdef CONFIG_NO_HZ - getnstimeofday(&xts); -#else xts = current_kernel_time(); -#endif tom = wall_to_monotonic; } while (read_seqretry(&xtime_lock, seq)); -- cgit v1.2.3 From a272378d1128d1c60a463a315646c86d174ff74c Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Sun, 19 Aug 2007 17:16:05 -0700 Subject: [KTIME]: Introduce ktime_sub_ns and ktime_sub_us First user will be the DCCP transport networking protocol. Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- kernel/hrtimer.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'kernel/hrtimer.c') diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index c21ca6bfaa66..dc8a4451d79b 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -277,6 +277,30 @@ ktime_t ktime_add_ns(const ktime_t kt, u64 nsec) } EXPORT_SYMBOL_GPL(ktime_add_ns); + +/** + * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable + * @kt: minuend + * @nsec: the scalar nsec value to subtract + * + * Returns the subtraction of @nsec from @kt in ktime_t format + */ +ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec) +{ + ktime_t tmp; + + if (likely(nsec < NSEC_PER_SEC)) { + tmp.tv64 = nsec; + } else { + unsigned long rem = do_div(nsec, NSEC_PER_SEC); + + tmp = ktime_set((long)nsec, rem); + } + + return ktime_sub(kt, tmp); +} + +EXPORT_SYMBOL_GPL(ktime_sub_ns); # endif /* !CONFIG_KTIME_SCALAR */ /* -- cgit v1.2.3