From: Terje Mathisen "terje.mathisen at on
nmm1(a)cam.ac.uk wrote:
> Well, yes, but that's no different from any other choice. As I have
> posted before, I favour a heterogeneous design on-chip:
>
> Essentially uninteruptible, user-mode only, out-of-order CPUs
> for applications etc.
> Interuptible, system-mode capable, in-order CPUs for the kernel
> and its daemons.

This forces the OS to effectively become a message-passing system, since
every single os call would otherwise require a pair of migrations
between the two types of cpus.

I'm not saying this would be bad though, since actual data could still
be passed as pointers...

Terje


--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
From: =?ISO-8859-1?Q?Niels_J=F8rgen_Kruse?= on
Andy "Krazy" Glew <ag-news(a)patten-glew.net> wrote:

> On 4/18/2010 4:57 AM, Niels J�rgen Kruse wrote:
> > Andy "Krazy" Glew<ag-news(a)patten-glew.net> wrote:
> >
> >> The ARM Cortex A9 CPU is out-of-order, and is becoming more and more
> >> widely used in things like cell phones and iPads.
> >
> > Cortex A9 is not shipping in any product yet (I believe). Lots of
> > preannouncements though. The Apple A4 CPU is currently believed to be a
> > tweaked Cortex A8, perhaps related to the tweaked A8 that Intrinsity did
> > for Samsung before being acquired by Apple.
>
> Ref?
>
> Most of the articles that I have seen say that the iPad A4 is a Cortex A9.

That would have been the early speculation. A more current view is
<http://www.anandtech.com/show/3640/apples-ipad-the-anandtech-review/16>
and the next page with benchmarks. The A4 is about half the speed of an
Atom N450 (512K Cache, 1.66 GHz) on a web page load benchmark. The hype
around the Cortex A9 would lead us to expect better.

--
Mvh./Regards, Niels J�rgen Kruse, Vanl�se, Denmark
From: Muzaffer Kal on
On Sun, 18 Apr 2010 11:25:38 -0700, "Andy \"Krazy\" Glew"
<ag-news(a)patten-glew.net> wrote:

>On 4/18/2010 4:57 AM, Niels J�rgen Kruse wrote:
>> Andy "Krazy" Glew<ag-news(a)patten-glew.net> wrote:
>>
>>> The ARM Cortex A9 CPU is out-of-order, and is becoming more and more
>>> widely used in things like cell phones and iPads.
>>
>> Cortex A9 is not shipping in any product yet (I believe). Lots of
>> preannouncements though. The Apple A4 CPU is currently believed to be a
>> tweaked Cortex A8, perhaps related to the tweaked A8 that Intrinsity did
>> for Samsung before being acquired by Apple.
>
>Ref?
>
>Most of the articles that I have seen say that the iPad A4 is a Cortex A9.

Based on my count of google results, A8 is slightly ahead of A9 in
terms of what core is actually in A4.
--
Muzaffer Kal

DSPIA INC.
ASIC/FPGA Design Services

http://www.dspia.com
From: jgd on
In article <4BCB60FF.9030306(a)patten-glew.net>, ag-news(a)patten-glew.net (
Glew) wrote:

> Itanium was designed by people who thought that P6-style out-of-order
> was going to fail.

Ah, that makes sense. Thanks. In some ways the Itanium method of running
several instructions at once seems more "obvious". I was convinced by it
at first, and only gradually realised that in spite of its intuitive
appeal, it did not work well in this example.

> In many ways they were the P6 competitors. P6 was Oregon. Itanium
> was California. Many Itanium folk were from P5.

If they had left P5 in the relatively early days, when clock speeds were
still under 100MHz, their implicit assumptions about speeds and
bandwidths make more sense. Thanks again.

--
John Dallman, jgd(a)cix.co.uk, HTML mail is treated as probable spam.
From: Robert Myers on
Andy "Krazy" Glew wrote:

>
> Hmm... From my point of view, the Itanium was the first computer
> architecture driven mainly by academics with PhDs.
>
> Its immediate predecessor, the P6, has only one PhD amongst its 5
> primary architects. (Bob Colwell.)
>
> Itanium had a lot more people who had piled it higher and deeper.

I am very grateful to the PhD academics who tolerated my eccentricities
as I pursued my PhD and for the education they gave me.

I am very grateful to the PhD academics who helped me to develop as an
independent thinker with some competence and self-confidence as I worked
outside academia.

I am very grateful to those who actually *do* things, with or without a
PhD, who continue to be generous with their knowledge and experience.

Scientists and engineers at every level of education are not the most
adept at negotiating political and social landscapes. I'm glad to have
people to talk to.

As to what is the foolproof way to manage the diverse range of talent
that is a multi-billion dollar R&D effort, I don't think there is such a
thing.

Robert.