Re: [PATCH 1/6] x86, 32-bit: Add new pt_regs stubs

From: H. Peter Anvin
Date: Wed Dec 09 2009 - 19:08:00 EST


On 12/09/2009 04:01 PM, Brian Gerst wrote:
> Add new stubs which add the pt_regs pointer as the last arg, matching
> 64-bit. This will allow these syscalls to be easily merged.
>
> Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
> +ptregs_##name: \
> + leal 4(%esp),%edx; \
> + movl PT_EBX(%edx),%eax; \
> + jmp sys_##name;

You're introducing a completely unnecessary pipeline serialization here.
Instead do:

movl (PT_EBX+4)(%esp),%eax;

... making the statements independent and therefore executable in parallel.

-hpa
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