Re: Performance improvement with Akira Tsukamoto's Athlon copy_user

[Manfred Spraul]

>I read the code of laze FPU state saving and confirmed that 
>if the function does not generate exception than
>'kernel_fpu_begin/end()' should assure fpu safe inside kernel.
>
>However, it is not enough where exception could rise, as Takahashi
>mentioned.

I had prototyped an exception safe kfpu framework, but then I didn't have the time to submit/cleanup it.

http://www.colorfullife.com/~manfred/linux-2.5/sse/patch-kfpu

Have you tried SSE based copy_to_user? With SSE, you can just save the affected registers, without unexpected sideeffects.

--
	Manfred