RE: [CFT][RFC] HT scheduler

[Nakajima, Jun]

> You forgot the one where no HT knowledge can be used for
optimizations.
> 
> - Asserting the CPU's #LOCK pin to take control of the system bus.
That in
>   MP system translate into the signaling CPU taking full control of
the
>   system bus until the pin is deasserted.
>

It is not the case with UP (single socket) using HT, where some
optimization for locks could be available. But you still need locks for
the logical processors.

	Jun

> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Davide Libenzi
> Sent: Tuesday, December 16, 2003 4:25 PM
> To: Linus Torvalds
> Cc: Jamie Lokier; Nick Piggin; bill davidsen; Linux Kernel Mailing
List
> Subject: Re: [CFT][RFC] HT scheduler
> 
> On Tue, 16 Dec 2003, Linus Torvalds wrote:
> 
> > I bet it is. In a big way.
> >
> > The lock does two independent things:
> >  - it tells the core that it can't just crack up the load and store.
> >  - it also tells other memory ops that they can't re-order around
it.
> 
> You forgot the one where no HT knowledge can be used for
optimizations.
> 
> - Asserting the CPU's #LOCK pin to take control of the system bus.
That in
>   MP system translate into the signaling CPU taking full control of
the
>   system bus until the pin is deasserted.
> 
> 
> 
> - Davide
> 
> 
> -
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