From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 45E961AF0DC for ; Wed, 19 Feb 2025 05:55:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739944552; cv=none; b=QFvUumSOu5HjT4wDL05VCjQtkjtgZui+M77bpOvOnBP4es52ZrIlg/lxZdo0XQf9vMmnOcM1XWo1gFWB6ZHYGA1h5YmZNAg8TL6l8TlG6uVecZ+UazOddUejObq+AUM9Q9k1xWeM8UVfEO3/f1Bpghl6iVHorl0wfTd2J313dJw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739944552; c=relaxed/simple; bh=WuKHW7I8g0i2VFxzixLMsnGBuOYV8ZWL0p4l8pQadao=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pdizSuKkAkYYXw95LQQWjvNDqUhzPVXBs/aRcyEDZZ0lY0I2eJ4L1zcaSy71Vhy+gTmdrNE6L+ragyqdR5pkzrM6xR/fxngAssT+ONto1o9XVLflc5sXiDQ97ITfHNU+n2JBpCZcpf69aiz8BBueDJ+VOM2A2wIOMpynJVjVDpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sH7QCyML; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sH7QCyML" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 682A3C4CED1; Wed, 19 Feb 2025 05:55:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1739944551; bh=WuKHW7I8g0i2VFxzixLMsnGBuOYV8ZWL0p4l8pQadao=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sH7QCyMLgkGb9oAam0oh7bLAvzvbzMTAn6taApioL++z85udjnMKP/sj6VWrZCX9T bzykAnbZB7/ID083W6rpbYgCKG08siO6fmaUcQtnCSkTQfxg4Cb1K/jqRs3ZUwiHOr W0NBO8M7+68k1sFNjA3rWpXW1gnMDU5FkPQ4O7Zc= Date: Wed, 19 Feb 2025 06:55:49 +0100 From: Greg KH To: Jay Wang Cc: stable@vger.kernel.org, David Woodhouse , Thomas Gleixner , Michael Kelley Subject: Re: [PATCH v5.10/v5.15/v6.1] x86/i8253: Disable PIT timer 0 when not in use Message-ID: <2025021959-headfirst-dayroom-c1bc@gregkh> References: <20250218203526.17408-1-wanjay@amazon.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250218203526.17408-1-wanjay@amazon.com> 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 > Signed-off-by: Thomas Gleixner > Tested-by: Michael Kelley > Link: https://lore.kernel.org/all/20240802135555.564941-1-dwmw2@infradead.org > Signed-off-by: Jay Wang > 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