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SubjectRe: Per-Processor Data Paget
On Mon, Dec 13, 1999 at 04:47:36PM -0800, Scott Lurndal wrote:
> > slurn@griffin.engr.sgi.com (Scott Lurndal) writes:
> >
> > >
> > > And what percentage of the time does a thread in the same address space
> > > get scheduled on a single processor.
> >
> > Also lots of apps simply rely on kernel thread for IO context. Aio is
> > implemented in glibc using cloned threads. Other programs use them e.g.
>
> There are additional forms of aio (much lower overhead) that don't rely
> on threads.

... which assumes that all programs are rewriten to use them first (a lot
of programs on Linux don't use the aio_* API, but use their threads to eat
mmap latencies etc.)

>
> > to tolerate paging latencies on mmap'ed files or for sendfile. For that it
> > makes sense to have a lot of threads per process on a single CPU, even on
> > a big multi CPU machine.
>
> Of course, but on a big multiCPU machine, it is not probable that two
> consecutively dispatched threads will be from the same address space.

WIth the current Linux scheduler it definitely is.

Do you have numbers on Irix that show otherwise?

-Andi

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