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From: Ingo Molnar <mingo@kernel.org>
To: "Brown, Len" <len.brown@intel.com>
Cc: Len Brown <lenb@kernel.org>, "x86@kernel.org" <x86@kernel.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/1] x86: replace cpu_up hard-coded mdelay with variable
Date: Mon, 20 Apr 2015 19:45:44 +0200	[thread overview]
Message-ID: <20150420174544.GA18931@gmail.com> (raw)
In-Reply-To: <1A7043D5F58CCB44A599DFD55ED4C94846861500@fmsmsx115.amr.corp.intel.com>


* Brown, Len <len.brown@intel.com> wrote:

> > What's the cutoff for 'modern hardware' - which CPUs stopped requiring
> > the delay?
> 
> This is the topic of ongoing research, and I'm not ready to send
> the patch setting a new default until I've heard back from a few more HW people.
> 
> Every system I've tested appears to work with delay 0.
> Were I to guess, I'd venture that every
> system that runs an X86_64 kernel might count as "modern" -- even
> the 2005 AMD Turion laptop I've got in the bone pile.

Could we use the apic version as a cutoff perhaps?

It would be nice to 'automatically' include modern 32-bit x86 systems 
as well.

Any failure here would be relatively easy to bisect to, so we might as 
well guess a bit and refine the quirk condition if needed?

Thanks,

	Ingo

  reply	other threads:[~2015-04-20 17:45 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-19  0:53 [PATCH 0/1] speeding up cpu_up() Len Brown
2015-04-19  0:53 ` [PATCH 1/1] x86: replace cpu_up hard-coded mdelay with variable Len Brown
2015-04-20  7:13   ` Ingo Molnar
2015-04-20 12:37     ` Brown, Len
2015-04-20 17:45       ` Ingo Molnar [this message]
2015-04-22  5:40   ` Paul Gortmaker
2015-04-22  6:07     ` Ingo Molnar
2015-05-01 21:02       ` Len Brown
2015-04-20  7:15 ` [PATCH 0/1] speeding up cpu_up() Ingo Molnar
2015-05-01 21:42   ` Len Brown
2015-05-01 22:47     ` Borislav Petkov
2015-05-02  0:42       ` Aravind Gopalakrishnan
2015-05-03 16:13         ` Aravind Gopalakrishnan
2015-05-04 22:45           ` Aravind Gopalakrishnan
2015-05-05  7:15             ` Borislav Petkov

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