From: "Joerg Roedel" <joerg.roedel@amd.com>
To: discuss@x86-64.org
Cc: "Andi Kleen" <ak@suse.de>, linux-kernel@vger.kernel.org
Subject: [PATCH 0/4] improve alternative instruction code and optimize get_cycles_sync
Date: Wed, 28 Feb 2007 15:05:01 +0100 [thread overview]
Message-ID: <20070228140501.GA19452@amd.com> (raw)
This series of patches extend the alternative instructions framework on
i386 and x86_64 architectures to support two alternative instruction
replacements. This code is used together with the introduction of the
X86_FEATURE_SYNC_RDTSC flag on i386 to simplify and optimize the
get_cycles_sync() function. The optimization changes this function to
use RDTSCP instead of CPUID;RDTSC if this instruction is available.
Don't use CPUID there is really important if the kernel runs as a KVM
guest, because this instruction is intercepted and causes an expensive
VMEXIT.
--
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG
next reply other threads:[~2007-02-28 14:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-28 14:05 Joerg Roedel [this message]
2007-02-28 14:14 ` [PATCH 1/4] i386: extend alternative instructions framework Joerg Roedel
2007-02-28 14:18 ` [PATCH 2/4] x86_64: changes to x86_64 architecture for alternative instruction improvements Joerg Roedel
2007-02-28 14:21 ` [PATCH 3/4] i386: add the X86_FEATURE_SYNC_RDTSC flag Joerg Roedel
2007-02-28 14:25 ` [PATCH 4/4] optimize and simplify get_cycles_sync() Joerg Roedel
2007-03-07 0:25 ` Andrew Morton
2007-03-09 9:57 ` Joerg Roedel
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