percpu: Optimize percpu accesses
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b4 am [email protected]Versions newest first
- v1 Latest3 patches 8 repliesIn review
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/3 | generic: Percpu infrastructure to rebase the per cpu area to zeroinclude/ include/ include/ +7 more | +50 | 0 replies | |
| 2/3 | x86_64: Fold pda into per cpu areaarch/ arch/ arch/ +4 more | +48 | 0 replies | |
| 3/3 | x86_64: Rebase per cpu variables to zeroarch/ arch/ arch/ +1 more | +9 | 0 replies |
Reviews trailers per patch
All 3 patches have a Reviewed-by or Acked-by of their own; the series has one for all of them.
| Patch | Christoph Lameter |
|---|---|
| Series | R-b |
| 1/3 | R-b |
| 2/3 | R-b |
| 3/3 | R-b |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.
Cover letter [PATCH 0/3] percpu: Optimize percpu accesses
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
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