From: Avi Kivity <avi@argo.co.il>
To: Joerg Roedel <joerg.roedel@amd.com>
Cc: discuss@x86-64.org, Andi Kleen <ak@suse.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4 TRY#3] optimize and simplify get_cycles_sync()
Date: Mon, 12 Mar 2007 18:08:11 +0200 [thread overview]
Message-ID: <45F57AEB.5030405@argo.co.il> (raw)
In-Reply-To: <20070312130245.GE8922@amd.com>
Joerg Roedel wrote:
> On Fri, Mar 09, 2007 at 08:10:03PM +0200, Avi Kivity wrote:
>
>> Joerg Roedel wrote:
>>
>>> From: Joerg Roedel <joerg.roedel@amd.com>
>>>
>>> This patch simplifies the get_cycles_sync() function by removing
>>> the #ifdefs from it. Further it introduces an optimization for AMD
>>> processors. There the RDTSCP instruction is used instead of CPUID;RDTSC
>>> which is helpfull if the kernel runs as a KVM guest. Running as a guest
>>> makes CPUID very expensive because it causes an intercept of the guest.
>>>
>>> +#define RDTSCP ".byte 0x0f, 0x01, 0xf9"
>>> + alternative_io_two("cpuid\nrdtsc",
>>> + "rdtsc", X86_FEATURE_SYNC_RDTSC,
>>> + ".byte 0x0f, 0x01, 0xf9", X86_FEATURE_RDTSCP,
>>>
>>>
>> why not use the RDTSCP macro here?
>>
>
> Does this macro exist? I couldn't found it in the current git tree. And
> the rdtscp macros in msr.h use the plain opcode too.
>
-ENOCOFFEE? You defined the macro 3 lines above the .byte directive...
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2007-03-12 16:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-09 15:08 [PATCH 0/4 TRY#3] improve alternative instruction code and optimize get_cycles_sync Joerg Roedel
2007-03-09 15:11 ` [PATCH 1/4 TRY#3] i386: extend alternative instructions framework Joerg Roedel
2007-03-09 15:12 ` [PATCH 2/4 TRY#3] x86_64: changes to x86_64 architecture for alternative instruction improvements Joerg Roedel
2007-03-09 15:13 ` [PATCH 3/4 TRY#3] i386: add the X86_FEATURE_SYNC_RDTSC flag Joerg Roedel
2007-03-09 15:15 ` [PATCH 4/4 TRY#3] optimize and simplify get_cycles_sync() Joerg Roedel
2007-03-09 18:10 ` Avi Kivity
2007-03-12 13:02 ` Joerg Roedel
2007-03-12 13:09 ` [discuss] " Andi Kleen
2007-03-12 13:21 ` Joerg Roedel
2007-03-12 13:29 ` Michael Matz
2007-03-12 13:45 ` Joerg Roedel
2007-03-12 16:08 ` Avi Kivity [this message]
2007-03-12 16:24 ` Joerg Roedel
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