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Re: On linux kernel packaging issue

> On Sat, Nov 08, 2003 at 10:58:03AM +0100, Eduard Bloch wrote:
> > #include <hallo.h>
> >
> > * Nikita V. Youshchenko [Sat, Nov 08 2003, 12:39:58PM]:
> > > Optimization is a serious issue too. Unlike most user space
> > > software, using 386 kernel on modern PC will cause serious
> > > performance loose. Especially if you consider mmx/sse/... and SMP
> > > issues. Note also that not all drivers are compatible with SMP,
> > > etc.
> >
> > Except of SMP, how exactly does optimisation of the KERNEL CODE help
> > you? Your filesystem driver may become 2-3% faster, but the disk
> > won't speed up at all, haha.
> Don't you have to compile the kernel for a CPU with MMX support to be
> able to use MMX in userspace? I understood something like that from the
> mplayer docs recently, but I may have misunderstood...

In theory, for proper "context-switch-safe" support for MMX, SSE and all 
other "modern x86" capabilities, corresponding code should present in 
context-switch routins of the kernel.

That code definitly exists in kernel compiled for 686 or k7. I don't know 
if it is compiled it when compiling 386 kernel. Anyone interested can 
look in the sources :).

2.6 kernels seem to have more CPU selection related options, including CPU 
selection and "compile support for other CPUs" switch.

I believe that it is generally beter to use kernel that corresponds to the 
CPU. This will make system more consistent.

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