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From: Ingo Molnar <mingo@kernel.org>
To: Len Brown <lenb@kernel.org>
Cc: x86@kernel.org, linux-pm@vger.kernel.org,
	linux-kernel@vger.kernel.org, Len Brown <len.brown@intel.com>,
	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 09:13:06 +0200	[thread overview]
Message-ID: <20150420071306.GA14315@gmail.com> (raw)
In-Reply-To: <87d69aab88c14d65ae1e7be55050d1b689b59b4b.1429402494.git.len.brown@intel.com>


* Len Brown <lenb@kernel.org> wrote:

> +config X86_INIT_MDELAY
> +	int "Milliseconds to wait to de-assert INIT upon CPU startup" if SMP
> +	range 0 10
> +	default "10"
> +	---help---
> +	  This allows you to specify how long the BSP will delay
> +	  between asserting INIT and de-asserting INIT when starting another CPU.
> +	  This delay is paid on each cpu-online operation, including boot-time,
> +	  resume from suspend, and resume from hibernate.  The the value of
> +	  10 millisec was specified by Multi-Processor Spec 1.4 in 1997.
> +	  But modern hardware does not require any delay.

What's the cutoff for 'modern hardware' - which CPUs stopped requiring 
the delay?

Also, is there any public document where the no-delay is specified for 
'modern hardware'?

Thanks,

	Ingo

  reply	other threads:[~2015-04-20  7:13 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 [this message]
2015-04-20 12:37     ` Brown, Len
2015-04-20 17:45       ` Ingo Molnar
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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