linux-kernel - Re: [PATCH] x86: Add a turbo mode sysctl

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Date:	Mon, 4 Apr 2016 09:48:23 +0300
From:	Nikolay Borisov <kernel@...p.com>
To:	Andy Lutomirski <luto@...nel.org>, x86@...nel.org
Cc:	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	linux-api@...r.kernel.org
Subject: Re: [PATCH] x86: Add a turbo mode sysctl

On 04/01/2016 06:49 PM, Andy Lutomirski wrote:
> Sadly, hardware turbo mode buttons are few and far between in these
> degenerate times.  Add a software control at /proc/sys/turbo_mode.
> 
> Unfortunately, Linux graphical environments have become very
> heavy-weight and are essentially unusable on non-Turbo systems.  The
> VT console works very well, though.
> 
> Due to KVM limitations, turbo mode is permanently on in a KVM guest.
> 
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
>  arch/x86/mm/pat.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 61 insertions(+), 2 deletions(-)

The name of the sysctl really sucks, it just control whether caching is
enabled/disabled. Now, having said that I realize there are multiple
sysctl that contain "cache" in their names. But can you come up with a
more descriptive name, directly relating to what the sysctl does and now
what its actual effects are :)? Also, aren't caches enabled by the
kernel when the system is booting, according to SDM1/section 9.3 caches
are disabled after reset and I assume the kernel does enable them when
it's booting?