From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <20080123044924.508382000@sgi.com> Date: Tue, 22 Jan 2008 20:49:24 -0800 From: travis@sgi.com Subject: [PATCH 0/3] percpu: Optimize percpu accesses Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton , Andi Kleen , mingo@elte.hu Cc: Christoph Lameter , jeremy@goop.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: This patchset provides the following: * Generic: Percpu infrastructure to rebase the per cpu area to zero This provides for the capability of accessing the percpu variables using a local register instead of having to go through a table on node 0 to find the cpu-specific offsets. It also would allow atomic operations on percpu variables to reduce required locking. * x86_64: Fold pda into per cpu area Declare the pda as a per cpu variable. This will move the pda area to an address accessible by the x86_64 per cpu macros. Subtraction of __per_cpu_start will make the offset based from the beginning of the per cpu area. Since %gs is pointing to the pda, it will then also point to the per cpu variables and can be accessed thusly: %gs:[&per_cpu_xxxx - __per_cpu_start] * x86_64: Rebase per cpu variables to zero Take advantage of the zero-based per cpu area provided above. Then we can directly use the x86_32 percpu operations. x86_32 offsets %fs by __per_cpu_start. x86_64 has %gs pointing directly to the pda and the per cpu area thereby allowing access to the pda with the x86_64 pda operations and access to the per cpu variables using x86_32 percpu operations. Based on 2.6.24-rc8-mm1 Signed-off-by: Mike Travis Reviewed-by: Christoph Lameter --- -- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org