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re: AMAP_SHARED (was Re: XIP)
> > > - For highly tuned, XIP'ed systems, programs should be designed to
> > > avoid .data, because they're COW'ed to page cache sooner or later.
> > why is this a problem?
> > if the data is needed, and it will be written to, then these pages
> > will be allocated (COW'd) eventually, and the same space will be used.
> Not a problem, as in it works.
> As already explained, we allocate PV for XIP segments, only for
> vnode-backed AMAP_SHARED == shared .data. Careful users may design
> the whole system to not allocate PV at all, by giving up that
> feature. To help user's design decision, I stated the obvious -
> .data is XIP-unfriendly.
but why is it unfriendly? i don't see why. there's going to
be the same number of pages allocated for writeable data in
both cases, so the same amount of resources will be consumed.
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