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
next prev parent 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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