On Tue, Feb 18, 2025 at 08:35:23PM +0000, Jay Wang wrote:
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: Jay Wang wanjay@amazon.com Cc: stable@vger.kernel.org #v5.10/v5.15/v6.1
arch/x86/kernel/i8253.c | 11 +++++++++-- drivers/clocksource/i8253.c | 13 +++++++++---- include/linux/i8253.h | 1 + 3 files changed, 19 insertions(+), 6 deletions(-)
Why don't you also want this in 6.6.y? You can't submit patches for only older kernels without them also being in newer ones, otherwise you will get a regression when upgrading.
Please always submit patches for all relevant kernel trees.
thanks,
greg k-h