diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2024-08-02 16:55:54 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-02-21 15:50:12 +0300 |
| commit | 25ffe92294ebcbd1109fb515fb0436cb8d10be4d (patch) | |
| tree | f9a1329fc7bf9bdafaf0bc1a0798d76c971a6927 /drivers/clocksource | |
| parent | 552e7938b4d7fe548fbf29b9950a14c6149d0470 (diff) | |
| download | linux-25ffe92294ebcbd1109fb515fb0436cb8d10be4d.tar.xz | |
x86/i8253: Disable PIT timer 0 when not in use
commit 70e6b7d9ae3c63df90a7bba7700e8d5c300c3c60 upstream.
Leaving the PIT interrupt running can cause noticeable steal time for
virtual guests. The VMM generally has a timer which toggles the IRQ input
to the PIC and I/O APIC, which takes CPU time away from the guest. Even
on real hardware, running the counter may use power needlessly (albeit
not much).
Make sure it's turned off if it isn't going to be used.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mhkelley@outlook.com>
Link: https://lore.kernel.org/all/20240802135555.564941-1-dwmw2@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/i8253.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c index d4350bb10b83..cb215e6f2e83 100644 --- a/drivers/clocksource/i8253.c +++ b/drivers/clocksource/i8253.c @@ -108,11 +108,8 @@ int __init clocksource_i8253_init(void) #endif #ifdef CONFIG_CLKEVT_I8253 -static int pit_shutdown(struct clock_event_device *evt) +void clockevent_i8253_disable(void) { - if (!clockevent_state_oneshot(evt) && !clockevent_state_periodic(evt)) - return 0; - raw_spin_lock(&i8253_lock); outb_p(0x30, PIT_MODE); @@ -123,6 +120,14 @@ static int pit_shutdown(struct clock_event_device *evt) } raw_spin_unlock(&i8253_lock); +} + +static int pit_shutdown(struct clock_event_device *evt) +{ + if (!clockevent_state_oneshot(evt) && !clockevent_state_periodic(evt)) + return 0; + + clockevent_i8253_disable(); return 0; } |