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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.