From: Borislav Petkov <bp@suse.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "Xue, Ken" <Ken.Xue@amd.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Li, Tony" <Tony.Li@amd.com>, "x86@kernel.org" <x86@kernel.org>,
"John Stultz" <john.stultz@linaro.org>,
"Aaron Lu" <aaron.lu@intel.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
"Suthikulpanit, Suravee" <Suravee.Suthikulpanit@amd.com>,
"Fengguang Wu" <fengguang.wu@intel.com>,
"Len Brown" <lenb@kernel.org>, "Huang Rui" <ray.huang@amd.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>
Subject: Re: [PATCH v2 1/4] x86, mwaitt: add monitorx and mwaitx instruction
Date: Tue, 9 Jun 2015 19:06:14 +0200 [thread overview]
Message-ID: <20150609170613.GI22105@pd.tnic> (raw)
In-Reply-To: <CALCETrWMRGzrMeWmEgESrBWL7A_B0m+sE5p_XMqXzvyVyxSwPg@mail.gmail.com>
On Tue, Jun 09, 2015 at 09:44:59AM -0700, Andy Lutomirski wrote:
> [1] For those who weren't bitten by this repeatedly, modern Intel CPUs
> (at least Sandy Bridge, anyway) will, by default, detect when all
> cores are in C1 or deeper, think to themselves "wow, the OS selected
> C1 -- it must want a very deep sleep indeed", and put the whole
> package into some kind of deep sleep state. The subsequent wakeup
> takes tens of milliseconds. Doing this in udelay would be awful.
That's a good point. Reportedly, the current MWAITX enters something
between C0 and C1 but the way I understood it, going forward, it will
enter deeper sleep states.
So for shallow C-states, your idle enter/exit latency is low enough but
I'd guess deeper states would be a problem.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-06-09 17:06 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-09 3:13 [PATCH v2 0/4] x86, mwaitt: introduce AMD mwaitt support Huang Rui
2015-06-09 3:13 ` [PATCH v2 1/4] x86, mwaitt: add monitorx and mwaitx instruction Huang Rui
2015-06-09 8:23 ` Peter Zijlstra
2015-06-09 9:48 ` Huang Rui
2015-06-09 10:05 ` Borislav Petkov
2015-06-09 16:44 ` Andy Lutomirski
2015-06-09 17:06 ` Borislav Petkov [this message]
2015-06-10 2:40 ` Huang Rui
2015-06-09 3:13 ` [PATCH v2 2/4] x86, mwaitt: make delay method configurable Huang Rui
2015-06-09 9:05 ` Borislav Petkov
2015-06-09 9:31 ` Peter Zijlstra
2015-06-09 10:03 ` Huang Rui
2015-06-09 10:08 ` Peter Zijlstra
2015-06-09 10:15 ` Huang Rui
2015-06-09 10:08 ` Borislav Petkov
2015-06-09 3:13 ` [PATCH v2 3/4] x86, mwaitt: introduce mwaix delay with a configurable timer Huang Rui
2015-06-09 8:31 ` Peter Zijlstra
2015-06-09 10:10 ` Huang Rui
2015-06-09 9:29 ` Peter Zijlstra
2015-06-09 10:59 ` Huang Rui
2015-06-09 16:46 ` Andy Lutomirski
2015-06-09 17:13 ` Peter Zijlstra
2015-06-09 17:55 ` Andy Lutomirski
2015-06-09 18:43 ` Borislav Petkov
2015-06-09 18:55 ` Andy Lutomirski
2015-06-12 8:42 ` Borislav Petkov
2015-06-12 23:15 ` Andy Lutomirski
2015-06-13 8:48 ` Borislav Petkov
2015-06-09 3:13 ` [PATCH v2 4/4] x86, mwaitt: add documents of delay option Huang Rui
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