[patch 3/3] timers: condense pending bitmap information

[Marcelo Tosatti <mtosatti@redhat.com>]

[-- Attachment #1: 03-optimize-pending-map-check --]
[-- Type: text/plain, Size: 1564 bytes --]

Condense the pending bitmap information in a bool.

Improves cyclictest results by 4us.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

---
 kernel/time/timer.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Index: linux-rt-devel/kernel/time/timer.c
===================================================================
--- linux-rt-devel.orig/kernel/time/timer.c	2019-04-15 14:22:56.000000000 -0300
+++ linux-rt-devel/kernel/time/timer.c	2019-04-15 14:24:24.803312280 -0300
@@ -206,6 +206,7 @@
 	unsigned int		cpu;
 	bool			is_idle;
 	bool			must_forward_clk;
+	bool			pending_map_clear;
 	DECLARE_BITMAP(pending_map, WHEEL_SIZE);
 	struct hlist_head	vectors[WHEEL_SIZE];
 } ____cacheline_aligned;
@@ -538,6 +539,7 @@
 {
 	hlist_add_head(&timer->entry, base->vectors + idx);
 	__set_bit(idx, base->pending_map);
+	base->pending_map_clear = false;
 	timer_set_idx(timer, idx);
 }
 
@@ -1741,6 +1743,9 @@
 		while (levels--)
 			expire_timers(base, heads + levels);
 	}
+	if (!housekeeping_cpu(base->cpu, HK_FLAG_TIMER) &&
+	    bitmap_empty(base->pending_map, WHEEL_SIZE))
+		base->pending_map_clear = true;
 	raw_spin_unlock_irq(&base->lock);
 	wakeup_timer_waiters(base);
 }
@@ -1784,10 +1789,10 @@
 #endif
 	base = this_cpu_ptr(&timer_bases[BASE_STD]);
 	if (!housekeeping_cpu(base->cpu, HK_FLAG_TIMER)) {
-		if (!bitmap_empty(base->pending_map, WHEEL_SIZE))
+		if (!base->pending_map_clear)
 			goto raise;
 		base++;
-		if (!bitmap_empty(base->pending_map, WHEEL_SIZE))
+		if (!base->pending_map_clear)
 			goto raise;
 
 		return;