Re: Re: Re: [RFC] PAGE_RW Should be added to PAGE_COPY ?

[Hugh Dickins]

On Fri, 15 Sep 2006, Yingchao Zhou wrote:
> >On Fri, 15 Sep 2006, Yingchao Zhou wrote:
> >> It's ok to mmap MAP_SHARED. But is it not a normal way to malloc() a space and
> >> then registered to NIC ?
> >
> >Not that I know of.  How would one register malloc()ed space to a NIC?
> >Sorry, I may well be misunderstanding you.
> The user-level NIC does this, eg. Myrinet...

Okay, thanks, I know nothing of that, and must defer to those who do.

But it sounds broken to me, in the way that you have described.

And the fix would not be to change the kernel's semantics for private
mappings, but for the app to use a shared mapping instead of a private.

Which would indeed be more work for the app than just using malloc,
since it needs some memory object (e.g. tmpfs file?) to map shared.

Hugh
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