From f16ff2bdb135e2eb35488264006b575c476ea597 Mon Sep 17 00:00:00 2001 From: Matt Redfearn Date: Thu, 19 Oct 2017 12:55:35 +0100 Subject: [PATCH] clocksource/drivers/mips-gic-timer: Add fastpath for local timer updates Always accessing the compare register via the CM redirect region is (relatively) slow. If the timer being updated is the current CPUs then this can be shortcutted by writing to the CM VP local region. Signed-off-by: Matt Redfearn Signed-off-by: Daniel Lezcano --- drivers/clocksource/mips-gic-timer.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c index 775dea04460d..a04808a21d4e 100644 --- a/drivers/clocksource/mips-gic-timer.c +++ b/drivers/clocksource/mips-gic-timer.c @@ -39,13 +39,18 @@ static u64 notrace gic_read_count(void) static int gic_next_event(unsigned long delta, struct clock_event_device *evt) { + int cpu = cpumask_first(evt->cpumask); u64 cnt; int res; cnt = gic_read_count(); cnt += (u64)delta; - write_gic_vl_other(mips_cm_vp_id(cpumask_first(evt->cpumask))); - write_gic_vo_compare(cnt); + if (cpu == raw_smp_processor_id()) { + write_gic_vl_compare(cnt); + } else { + write_gic_vl_other(mips_cm_vp_id(cpu)); + write_gic_vo_compare(cnt); + } res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0; return res; } -- 2.45.2