Re: [Xen-devel] [PATCH 7/7] introduce write-once optimization

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 22.09.09 10:27 >>>
>On 21/09/2009 13:12, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
>
>> This one is likely the most questionable part: Realizing that the
>> compiler can do a much better job in terms of CSE when the variables
>> needed are constant, this introduces and extension to the read-mostly
>> variables, allowing variables to be marked as being written just
>> during boot initialization.
>
>How much of a win overall was this? The main concern comes from mixing the
>two aliased variables within a single linkage unit, where it will be hard to
>know how clever the compiler might be with inlining and inter-function
>optimisations.

About 8k (5k compressed) code size reduction, I think. I didn't measure
performance.

Jan


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