linux-kernel - [PATCH 4/4 TRY#3] optimize and simplify get_cycles

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Message-ID: <20070309151511.GE13481@amd.com>
Date:	Fri, 9 Mar 2007 16:15:11 +0100
From:	"Joerg Roedel" <joerg.roedel@....com>
To:	discuss@...-64.org
cc:	"Andi Kleen" <ak@...e.de>, linux-kernel@...r.kernel.org
Subject: [PATCH 4/4 TRY#3] optimize and simplify get_cycles_sync()

From: Joerg Roedel <joerg.roedel@....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.

Signed-off-by: Joerg Roedel <joerg.roedel@....com>

-- 
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG

View attachment "optimized-get_cycles_sync.patch" of type "text/plain" (1808 bytes)