Messages in this thread | | | Date | Tue, 05 Jul 2011 10:47:10 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [Q x86-64] on kernel_eflags |
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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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