Re: [PATCH -mm crypto] AES: x86_64 asm implementation optimization

[Sebastian Siewior]

* Huang, Ying | 2008-04-09 14:41:02 [+0800]:

>This patch increases the performance of AES x86-64 implementation. The
>average increment is more than 6.3% and the max increment is
>more than 10.2% on Intel CORE 2 CPU. The performance increment is
>gained via the following methods:
>
>- Two additional temporary registers are used to hold the subset of
>  the state, so that the dependency between instructions is reduced.
>
>- The expanded key is loaded via 2 64bit load instead of 4 32-bit load.
>

>From your description I would assume that the performance can only
increase. However, on my
|model name      : AMD Athlon(tm) 64 Processor 3200+
the opposite is the case [1], [2]. I dunno why and I didn't mixup
patched & unpached :). I checked this patch on
|model name      : Intel(R) Core(TM)2 CPU         T7200  @ 2.00GHz
and the performance really increases [3], [4].

[1] http://download.breakpoint.cc/aes_patch/patched.txt
[2] http://download.breakpoint.cc/aes_patch/unpatched.txt
[3] http://download.breakpoint.cc/aes_patch/perf_patched.txt
[4] http://download.breakpoint.cc/aes_patch/perf_originall.txt

>---
> arch/x86/crypto/aes-x86_64-asm_64.S |  101 ++++++++++++++++++++----------------
> include/crypto/aes.h                |    1 
> 2 files changed, 58 insertions(+), 44 deletions(-)
>
>--- a/include/crypto/aes.h
>+++ b/include/crypto/aes.h
>@@ -19,6 +19,7 @@
> 
> struct crypto_aes_ctx {
> 	u32 key_length;
>+	u32 _pad1;

Why is this pad required? Do you want special alignment of the keys?

> 	u32 key_enc[AES_MAX_KEYLENGTH_U32];
> 	u32 key_dec[AES_MAX_KEYLENGTH_U32];
> };
>

Sebastian
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