Re: getting processor numbers

H. Peter Anvin
2007-04-04T05:18:33Z

Eric Dumazet wrote:
>
> There is one thing that always worried me.
>
> Intel & AMD manuals make clear that mixing data and program in the same
> page is bad for performance.
>
> In particular, x86_64 vsyscall put jiffies and other
> vsyscall_gtod_data_t right in the midle of code. That is certainly not
> wise.
>
> A probably sane implementation should use two pages, one for code, one
> for data.
>

Mutable data should be separated from code. I think any current CPU
will do fine as long as they are in separate 128-byte chunks, but they
need at least that much separation.

Readonly data does not need to be separated from code.

-hpa