Re: How to find out which pages were copied-on-write?

[Michael Clark]

On 07/13/04 01:21, Lutz Vieweg wrote:
> Michael Clark wrote:
>
> > HPAs library LPSM sounds like what you're looking for.
> >
> > http://freshmeat.net/projects/lpsm/
> >
> > Or you can do what you want the hard way using mprotect and a SEGV 
> > handler.
>
>
> Certainly a valid idea to consider - doing all those things in 
> userspace... so
> thanks for the hint!
>
> But wouldn't that introduce a significant overhead and undermine all of the
> nice advantages the kernel might have in scheduling I/O operations?

Not really. Plain read/write IO is generally faster than mmap IO anyway.
You don't use mmap for speed but rather for convenience.

> However, I shall really consider and profile the mprotect/sighandler 
> approach...
>
> Regards,
>
> Lutz Vieweg
>
> PS: I'm using my own allocator already, so using the C-library 
> implementation
>     wouldn't gain me much...

This wasn't why I suggested it. It's has the commit semantics
on memory mapped files that you were asking about (the allocator
is optional I believe).

~mc
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