linux-kernel - Re: [PATCH 2/2] x86: speed cpu_up by quirking cpu_init

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Message-ID: <20150508082319.GA4137@pd.tnic>
Date:	Fri, 8 May 2015 10:23:20 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Len Brown <lenb@...nel.org>, x86@...nel.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Len Brown <len.brown@...el.com>
Subject: Re: [PATCH 2/2] x86: speed cpu_up by quirking cpu_init_udelay

On Fri, May 08, 2015 at 09:51:11AM +0200, Ingo Molnar wrote:
> > +static const struct x86_cpu_id init_udelay_ids[] = {
> > +	{ X86_VENDOR_INTEL, 0x6, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{ X86_VENDOR_AMD, 0x16, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{ X86_VENDOR_AMD, 0x15, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{ X86_VENDOR_AMD, 0x14, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{ X86_VENDOR_AMD, 0x12, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{ X86_VENDOR_AMD, 0x11, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{ X86_VENDOR_AMD, 0x10, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{ X86_VENDOR_AMD, 0xF, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
> > +	{}
> > +};
> 
> So since especially AMD likes to iterate the family upwards, why not 
> make this a simple open ended check:
> 
> 	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
> 	    boot_cpu_data.x86 >= 6 ||
> 	    boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
> 	    boot_cpu_data.x86 >= 15) {
> 
> 		... 0 delay ...
> 	}
> 
> ... which is much smaller and more future proof?

I was about to say that...

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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