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Date: Tue, 18 Feb 2025 08:17:52 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: jaywang-amazon <wanjay@amazon.com>
Cc: stable@vger.kernel.org
Subject: Re: [PATCH 6.1 1/1] x86/i8253: Disable PIT timer 0 when not in use
Message-ID: <2025021834-overdrawn-rely-d929@gregkh>
References: <20250217225353.21795-2-wanjay@amazon.com>
 <20250217225353.21795-4-wanjay@amazon.com>
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In-Reply-To: <20250217225353.21795-4-wanjay@amazon.com>

On Mon, Feb 17, 2025 at 10:53:55PM +0000, jaywang-amazon wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> 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
> 
> (cherry picked from commit 70e6b7d9ae3c63df90a7bba7700e8d5c300c3c60)
> Cc: stable@vger.kernel.org #v6.1
> Signed-off-by: jaywang-amazon <wanjay@amazon.com>

We need a real name, not a fake-company name please.

thanks,

greg k-h