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SubjectRe: Per-Processor Data Paget
Date
> 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.
>
> Most Linux systems still run with a single CPU, so I would guess "most".
> At least they cannot be ignored.

And of course a per-processor datapage is not necessary nor
required on a non SMP system, right?

>
> 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.

> 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.

scott

>
>
> -Andi
>


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