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;
+
next = timerqueue_getnext(&base->active);
if (!next)
continue;
@@ -1441,6 +1444,9 @@ void hrtimer_run_queues(void)
return;
for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
+ if (!(cpu_base->active_bases & (1 << index)))
+ continue;
+
base = &cpu_base->clock_base[index];
if (!timerqueue_getnext(&base->active))
continue;
@@ -1681,6 +1687,8 @@ static void migrate_hrtimers(int scpu)
raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
+ if (!(old_base->active_bases & (1 << i)))
+ continue;
migrate_hrtimer_list(&old_base->clock_base[i],
&new_base->clock_base[i]);
}
Now the code size increase is in a sane range:
x86_64 i386 ARM power
Mainline 7668 6942 8077 10253
+ patch 7748 6990 8113 10365
+80 +48 +36 +112
So your variant is at least 5 times larger than the simple and obvious
solution.
I told you before to look at the resulting binary code changes and
sanity check whether they are in the right ball park.
Thanks,
tglx
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