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SubjectRe: [Q x86-64] on kernel_eflags
On 07/05/2011 03:47 AM, Cyrill Gorcunov wrote:
>
> Should not every cpu has own copy of kernel_eflags? Just
> to be consistent in style? Or this would be space waisting
> and an optimization is done here?
>

Not specific to this particular case, but in general: a shared variable
that used often but rarely written to will automatically replicate
itself in the caches of multiple processors. This is the purpose of the
read_mostly segment (writes are permitted but expected to be rare),
which exists to make sure that a frequently written variable doesn't
randomly end up in the cache line next to a read-mostly variable.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.



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