From: Ingo Molnar <mingo@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linaro-kernel@lists.linaro.org, linux-kernel@vger.kernel.org,
Preeti U Murthy <preeti@linux.vnet.ibm.com>
Subject: [PATCH] hrtimer: Replace cpu_base->active_bases with a direct check of the active list
Date: Thu, 9 Apr 2015 08:28:41 +0200 [thread overview]
Message-ID: <20150409062841.GB14259@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1504082019220.3845@nanos>
* Thomas Gleixner <tglx@linutronix.de> wrote:
> On Tue, 7 Apr 2015, Viresh Kumar wrote:
>
> > At several instances we iterate over all possible clock-bases for a
> > particular cpu-base. Whereas, we only need to iterate over active bases.
> >
> > We already have per cpu-base 'active_bases' field, which is updated on
> > addition/removal of hrtimers.
> >
> > This patch creates for_each_active_base(), which uses 'active_bases' to
> > iterate only over active bases.
>
> I'm really not too excited about this incomprehensible macro mess and
> especially not about the code it generates.
>
> x86_64 i386 ARM power
>
> Mainline 7668 6942 8077 10253
>
> + Patch 8068 7294 8313 10861
>
> +400 +352 +236 +608
>
> That's insane.
>
> What's wrong with just adding
>
> if (!(cpu_base->active_bases & (1 << i)))
> continue;
>
> to the iterating sites?
>
> Index: linux/kernel/time/hrtimer.c
> ===================================================================
> --- linux.orig/kernel/time/hrtimer.c
> +++ linux/kernel/time/hrtimer.c
> @@ -451,6 +451,9 @@ static ktime_t __hrtimer_get_next_event(
> struct timerqueue_node *next;
> struct hrtimer *timer;
>
> + if (!(cpu_base->active_bases & (1 << i)))
> + continue;
> +
Btw., does cpu_base->active_bases even make sense? hrtimer bases are
fundamentally percpu, and to check whether there are any pending
timers is a very simple check:
base->active->next != NULL
So I'd rather suggest taking a direct look at the head, instead of
calculating bit positions, masks, etc.
Furthermore, we never actually use cpu_base->active_bases as a
'summary' value (which is the main point of bitmasks in general), so
I'd remove that complication altogether.
This would speed up various hrtimer primitives like
hrtimer_remove()/add and simplify the code. It would be a net code
shrink as well.
Totally untested patch below. It gives:
text data bss dec hex filename
7502 427 0 7929 1ef9 hrtimer.o.before
7422 427 0 7849 1ea9 hrtimer.o.after
and half of that code removal is from hot paths.
This would simplify the followup step of skipping over inactive bases
as well.
Thanks,
Ingo
include/linux/hrtimer.h | 2 --
kernel/time/hrtimer.c | 7 ++-----
2 files changed, 2 insertions(+), 7 deletions(-)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 05f6df1fdf5b..d65b858a94c1 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -166,7 +166,6 @@ enum hrtimer_base_type {
* @lock: lock protecting the base and associated clock bases
* and timers
* @cpu: cpu number
- * @active_bases: Bitfield to mark bases with active timers
* @clock_was_set: Indicates that clock was set from irq context.
* @expires_next: absolute time of the next event which was scheduled
* via clock_set_next_event()
@@ -182,7 +181,6 @@ enum hrtimer_base_type {
struct hrtimer_cpu_base {
raw_spinlock_t lock;
unsigned int cpu;
- unsigned int active_bases;
unsigned int clock_was_set;
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires_next;
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 76d4bd962b19..63e21df6c086 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -848,7 +848,6 @@ static int enqueue_hrtimer(struct hrtimer *timer,
debug_activate(timer);
timerqueue_add(&base->active, &timer->node);
- base->cpu_base->active_bases |= 1 << base->index;
/*
* HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
@@ -892,8 +891,6 @@ static void __remove_hrtimer(struct hrtimer *timer,
}
#endif
}
- if (!timerqueue_getnext(&base->active))
- base->cpu_base->active_bases &= ~(1 << base->index);
out:
timer->state = newstate;
}
@@ -1268,10 +1265,10 @@ void hrtimer_interrupt(struct clock_event_device *dev)
struct timerqueue_node *node;
ktime_t basenow;
- if (!(cpu_base->active_bases & (1 << i)))
+ base = cpu_base->clock_base + i;
+ if (!base->active.next)
continue;
- base = cpu_base->clock_base + i;
basenow = ktime_add(now, base->offset);
while ((node = timerqueue_getnext(&base->active))) {
next prev parent reply other threads:[~2015-04-09 6:28 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-07 2:10 [PATCH V2 0/2] hrtimer: Iterate only over active clock-bases Viresh Kumar
2015-04-07 2:10 ` [PATCH V2 1/2] hrtimer: update '->active_bases' before calling hrtimer_force_reprogram() Viresh Kumar
2015-04-22 19:04 ` [tip:timers/core] hrtimer: Update active_bases " tip-bot for Viresh Kumar
2015-04-07 2:10 ` [PATCH V2 2/2] hrtimer: Iterate only over active clock-bases Viresh Kumar
2015-04-08 12:10 ` Peter Zijlstra
2015-04-08 20:11 ` Thomas Gleixner
2015-04-09 2:42 ` Viresh Kumar
2015-04-09 6:28 ` Ingo Molnar [this message]
2015-04-09 6:38 ` [PATCH] hrtimer: Replace cpu_base->active_bases with a direct check of the active list Ingo Molnar
2015-04-09 6:39 ` [PATCH] hrtimer: Only iterate over active bases in migrate_hrtimers() Ingo Molnar
2015-04-09 6:53 ` [PATCH] hrtimer: Replace timerqueue_getnext() uses with direct access to 'active.next' Ingo Molnar
2015-04-09 7:10 ` [PATCH] hrtimers: Use consistent variable names for timerqueue_node iterations Ingo Molnar
2015-04-09 6:57 ` [PATCH] hrtimer: Replace cpu_base->active_bases with a direct check of the active list Peter Zijlstra
2015-04-09 7:09 ` Ingo Molnar
2015-04-09 7:20 ` Ingo Molnar
2015-04-09 8:58 ` Thomas Gleixner
2015-04-09 8:58 ` Peter Zijlstra
2015-04-09 9:18 ` Thomas Gleixner
2015-04-09 9:31 ` Peter Zijlstra
2015-04-09 9:56 ` Thomas Gleixner
2015-04-13 5:53 ` Preeti U Murthy
2015-04-13 7:53 ` Thomas Gleixner
2015-04-09 8:03 ` Peter Zijlstra
2015-04-09 8:10 ` Ingo Molnar
2015-04-09 8:53 ` Thomas Gleixner
2015-04-09 9:18 ` Ingo Molnar
2015-04-14 21:08 [patch 00/39] hrtimer/tick: Optimizations, cleanups and solutions for various issues Thomas Gleixner
2015-04-14 21:08 ` [patch 01/39] hrtimer: Update active_bases before calling hrtimer_force_reprogram() Thomas Gleixner
2015-04-14 21:08 ` [patch 02/39] hrtimer: Get rid of the resolution field in hrtimer_clock_base Thomas Gleixner
2015-04-15 6:29 ` Frans Klaver
2015-04-15 6:32 ` Frans Klaver
2015-04-20 8:34 ` Preeti U Murthy
2015-04-22 19:05 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 03/39] net: sched: Use hrtimer_resolution instead of hrtimer_get_res() Thomas Gleixner
2015-04-16 16:04 ` David Miller
2015-04-22 19:05 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 04/39] sound: " Thomas Gleixner
2015-04-14 21:08 ` Thomas Gleixner
2015-04-16 8:07 ` Takashi Iwai
2015-04-16 8:07 ` Takashi Iwai
2015-04-16 9:08 ` Thomas Gleixner
2015-04-22 19:05 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 05/39] hrtimer: Get rid " Thomas Gleixner
2015-04-22 19:05 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 06/39] hrtimer: Make the statistics fields smaller Thomas Gleixner
2015-04-22 19:06 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 07/39] hrtimer: Get rid of softirq time Thomas Gleixner
2015-04-22 19:06 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 08/39] hrtimer: Make offset update smarter Thomas Gleixner
2015-04-20 9:30 ` Preeti U Murthy
2015-04-22 19:06 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 09/39] hrtimer: Use a bits for various boolean indicators Thomas Gleixner
2015-04-22 19:07 ` [tip:timers/core] hrtimer: Use " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 10/39] hrtimer: Use cpu_base->active_base for hotpath iterators Thomas Gleixner
2015-04-20 11:16 ` Preeti U Murthy
2015-04-21 11:53 ` Thomas Gleixner
2015-04-22 3:13 ` Preeti U Murthy
2015-04-22 19:07 ` [tip:timers/core] hrtimer: Use cpu_base-> active_base " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 11/39] hrtimer: Cache line align the hrtimer cpu base Thomas Gleixner
2015-04-22 19:07 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 12/39] hrtimer: Align the hrtimer clock bases as well Thomas Gleixner
2015-04-22 19:07 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 13/39] timerqueue: Let timerqueue_add/del return information Thomas Gleixner
2015-04-22 19:08 ` [tip:timers/core] timerqueue: Let timerqueue_add/ del " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 14/39] hrtimer: Make use of timerqueue_add/del return values Thomas Gleixner
2015-04-22 19:08 ` [tip:timers/core] hrtimer: Make use of timerqueue_add/ del " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 15/39] hrtimer: Keep pointer to first timer and simplify __remove_hrtimer() Thomas Gleixner
2015-04-22 19:08 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 16/39] hrtimer: Get rid of hrtimer softirq Thomas Gleixner
2015-04-22 19:09 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 17/39] tick: sched: Remove hrtimer_active() checks Thomas Gleixner
2015-04-16 13:37 ` Frederic Weisbecker
2015-04-22 19:09 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 18/39] tick: sched: Force tick interrupt and get rid of softirq magic Thomas Gleixner
2015-04-22 14:22 ` Frederic Weisbecker
2015-04-22 14:32 ` Thomas Gleixner
2015-04-23 11:47 ` Frederic Weisbecker
2015-04-23 13:07 ` Thomas Gleixner
2015-04-23 16:14 ` Frederic Weisbecker
2015-04-22 19:09 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 19/39] tick: sched: Restructure code Thomas Gleixner
2015-04-22 19:09 ` [tip:timers/core] tick: Sched: " tip-bot for Thomas Gleixner
2015-04-14 21:08 ` [patch 20/39] tick: nohz: Rework next timer evaluation Thomas Gleixner
2015-04-16 16:42 ` Paul E. McKenney
2015-04-21 12:04 ` Thomas Gleixner
2015-04-22 19:10 ` [tip:timers/core] tick: Nohz: " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 21/39] x86: perf: Use hrtimer_start() Thomas Gleixner
2015-04-22 19:10 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 22/39] x86: perf: uncore: " Thomas Gleixner
2015-04-22 19:10 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 23/39] perf: core: " Thomas Gleixner
2015-04-22 19:11 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 24/39] sched: core: Use hrtimer_start[_expires]() Thomas Gleixner
2015-04-22 19:11 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 25/39] sched: deadline: Use hrtimer_start() Thomas Gleixner
2015-04-22 19:11 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 26/39] hrtimer: Get rid of __hrtimer_start_range_ns() Thomas Gleixner
2015-04-22 19:11 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 27/39] hrtimer: Make hrtimer_start() a inline wrapper Thomas Gleixner
2015-04-22 19:12 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 28/39] hrtimer: Remove bogus hrtimer_active() check Thomas Gleixner
2015-04-22 19:12 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 29/39] hrtimer: Rmove " Thomas Gleixner
2015-04-22 19:12 ` [tip:timers/core] futex: Remove " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 30/39] rtmutex: " Thomas Gleixner
2015-04-22 19:13 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 31/39] net: core: pktgen: " Thomas Gleixner
2015-04-16 16:04 ` David Miller
2015-04-22 19:13 ` [tip:timers/core] net: core: pktgen: Remove bogus hrtimer_active( ) check tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 32/39] alarmtimer: Get rid of unused return value Thomas Gleixner
2015-04-22 19:13 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 34/39] tick: broadcast-hrtimer: Remove overly clever return value abuse Thomas Gleixner
2015-04-17 10:33 ` Preeti U Murthy
2015-04-22 19:13 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 35/39] hrtimer: Remove hrtimer_start() return value Thomas Gleixner
2015-04-22 19:14 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 36/39] hrtimer: Avoid locking in hrtimer_cancel() if timer not active Thomas Gleixner
2015-04-22 19:14 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 37/39] staging: ozwpan: Remove hrtimer_active() check Thomas Gleixner
2015-04-14 21:09 ` [patch 38/39] timer: Remove pointless return value of do_usleep_range() Thomas Gleixner
2015-04-22 19:14 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-04-14 21:09 ` [patch 39/39] timer: Put usleep_range into the __sched section Thomas Gleixner
2015-04-22 19:14 ` [tip:timers/core] " tip-bot for Thomas Gleixner
[not found] ` <20150414203503.322172417@linutronix.de>
2015-04-14 21:38 ` [patch 33/39] power: reset: ltc2952: Remove bogus hrtimer_start() return value checks Frans Klaver
2015-04-30 15:49 ` Sebastian Reichel
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