Re: Thread implementations...

Larry McVoy (lm@bitmover.com)
Fri, 26 Jun 1998 08:34:02 -0700


: Lets assume
:
: 1) The mmap is readonly

That doesn't help, as explained below.

: > Your example above is passing a mmap region to write(). Unless you go
: > teach write about page flipping, or unless you lock the pages and sleep
: > the process calling write, you have to bcopy out of the mmapped region
: > into the destination pages (or skb buffers).
:
: If we mapped read-only then you don't need sleep-on-write, you
: just need sleep-on-unmap or -remap. If we mapped r-w, we fall
: back to the current behaviour.

What about all the other processes in the system that may touch this data?
Allowing that breaks the write() semantics.

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