Re: Intel P6 vs P7 system call performance

billyrose@billyrose.net
Thu, 19 Dec 2002 13:46:30 -0500


> Not true. A ret(urn) is (sort of) equivalent to 'pop %eip'. The above
> code would actually jump to address 0xfffff000, but probably be slow
> since it confuses the branch prediction.
>
>
>Bart

that being the case, then the original code that Linus put forth:

pushl $0xfffff000
call *(%esp)
add $4,%esp

would be the way to go as it is highly readable. actually, the code at
0xfffff000 could issue a ret $4 and eliminate the add after the call.

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