Re: X15 alpha release: as fast as TUX but in user space (fwd)

Richard Gooch
2001-04-29T18:48:30Z

Ingo Oeser writes:
> On Sun, Apr 29, 2001 at 04:27:48AM -0700, David S. Miller wrote:
> > The idea is that the one thing one tends to optimize for new cpus
> > is the memcpy/memset implementation. What better way to shield
> > libc from having to be updated for new cpus but to put it into
> > the kernel in this magic page?
>
> Hehe, you have read this MXT patch on linux-mm, too? ;-)
>
> There we have 10x faster memmove/memcpy/bzero for 1K blocks
> granularity (== alignment is 1K and size is multiple of 1K), that
> is done by the memory controller.

This sounds different to me. Using the memory controller is (should
be!) a privileged operation, thus it requires a system call. This is
quite different from code in a magic page, which is excuted entirely
in user-space. The point of the magic page is to avoid the syscall
overhead.

Regards,

Richard....
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