From: Huang Rui <ray.huang@amd.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Borislav Petkov" <bp@suse.de>,
"Andy Lutomirski" <luto@amacapital.net>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Len Brown" <lenb@kernel.org>,
"John Stultz" <john.stultz@linaro.org>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
"Fengguang Wu" <fengguang.wu@intel.com>,
"Aaron Lu" <aaron.lu@intel.com>,
"Suravee Suthikulanit" <suravee.suthikulpanit@amd.com>,
"Tony Li" <tony.li@amd.com>, "Ken Xue" <ken.xue@amd.com>
Subject: Re: [PATCH v5 1/2] x86, mwaitt: add monitorx and mwaitx instruction
Date: Mon, 15 Jun 2015 20:42:58 +0800 [thread overview]
Message-ID: <20150615124257.GA28310@hr-slim.amd.com> (raw)
In-Reply-To: <20150615105542.GV3644@twins.programming.kicks-ass.net>
On Mon, Jun 15, 2015 at 12:55:42PM +0200, Peter Zijlstra wrote:
> On Mon, Jun 15, 2015 at 06:48:03PM +0800, Huang Rui wrote:
> > +/*
> > + * MWAITT allows for both a timer value to get you out of the MWAIT as
> > + * well as the normal exit conditions.
> > + *
> > + * MWAITX ECX[1]: enable timer if set
> > + * MWAITX EBX[31:0]: max wait time expressed in SW P0 clocks
> > + *
> > + * Below is the compared data between MWAIT and MWAITX on AMD
> > + * processors:
> > + * MWAIT MWAITX
> > + * opcode 0f 01 c9 | 0f 01 fb
> > + * ECX[0] value of RFLAGS.IF seen by instruction
> > + * ECX[1] unused/#GP if set | enable timer if set
> > + * ECX[31:2] unused/#GP if set
> > + * EAX unused (reserve for hint)
>
> Seeing how you're stuffing a !0 value in here in the next patch, the
> above comment seems slightly incorrect, no?
>
That's because current processor doesn't support to go C1 state.
The next patch use the hint is to avoid core go to C1 state in future
processor.
Thanks,
Rui
next prev parent reply other threads:[~2015-06-15 12:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 10:48 [PATCH v5 0/2] x86, mwaitt: introduce AMD mwaitt support Huang Rui
2015-06-15 10:48 ` [PATCH v5 1/2] x86, mwaitt: add monitorx and mwaitx instruction Huang Rui
2015-06-15 10:55 ` Peter Zijlstra
2015-06-15 12:42 ` Huang Rui [this message]
2015-06-15 10:48 ` [PATCH v5 2/2] x86, mwaitt: introduce mwaix delay with a configurable timer Huang Rui
2015-06-15 10:57 ` Peter Zijlstra
2015-06-15 11:15 ` Borislav Petkov
2015-06-15 14:04 ` Huang Rui
2015-06-15 14:25 ` Borislav Petkov
2015-06-15 14:33 ` Huang Rui
2015-06-15 14:14 ` Huang Rui
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