From: "Joerg Roedel" <joerg.roedel@amd.com>
To: "Avi Kivity" <avi@argo.co.il>
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 14:02:45 +0100 [thread overview]
Message-ID: <20070312130245.GE8922@amd.com> (raw)
In-Reply-To: <45F1A2FB.7040206@argo.co.il>
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.
Regards,
Joerg
--
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG
next prev parent reply other threads:[~2007-03-12 13:04 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 [this message]
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
2007-03-12 16:24 ` Joerg Roedel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070312130245.GE8922@amd.com \
--to=joerg.roedel@amd.com \
--cc=ak@suse.de \
--cc=avi@argo.co.il \
--cc=discuss@x86-64.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox