| Ranando King 2004-11-15, 5:45 pm |
| Ok.... I just got done reading this entire thread, and it seems to me that
most if not all of you missed the point. Linux doesn't need to be altered
significantly to handle such an architecture. Since linux can already handle
SMP and IHT processor setups, it already has all the technology it's going
to need built in. Such a chip as the Niagara will simply appear as a 32 chip
SMP system.
Now as far as application performance goes, you need to consider a few
things:
1. Every process under Linux is a kernel thread.
2. Every process fork and pthread is a kernel thread
So what does this mean? It means a BIG bonus to performance even under the
currently stable kernel design. Why? Simple. If you have a common Linux
setup, you're most likely running upwards of 150+ threads simultaneously.
Now, let's assume you've only got 128 processes going and do some really
easy math.
On average only 1/8th of the threads on a system are actively using time
slices. The rest of them are in some form of IO wait. So that means we've
only got to worry about 16 of those threads. Mind you, that doesn't include
the kernel itself, but for now, we'll just assume (incorrectly) that the
kernel only acts in response to application actions. That means we can count
the kernel's CPU time as part of the time used by those 16 threads.
On a single 1024MHz CPU, each thread will receive about 64MHz of bandwidth,
max.
On a SMP system with 4 1024MHz CPUs, each thread gets 256MHz max.
On a Niagara system at 1024MHz, each thread will get the full 1024MHz of
bandwith for as long as it needs it.... well maybe. Since there are 8 cores,
each thread will get the full benefit of the 1024Mhz bandwith if those 16
active threads represent 8 or less process instances.
My point is that normal, single threaded applications will still benefit
from this kind of architecture simply because there will be less competition
between applications for time on any given core and less competition between
application threads on any 1 core. Sure, for any 1 application to reap the
biggest benefit from the Niagara system it would need to be broken into
thread groups, each group working together as tightly as possible but as
independantly as possible from other groups. But on the whole, a 1GHz
Niagara processor should easily make the latest & greatest 4+ GHz P4 look
like a bad joke.
R. King
"Charles Prudhomme" <cp@rogers.com> wrote in message
news:bIidnUprE8kkhgvcRVn-uQ@rogers.com...
> Overhaul Linux Kernel to support Massive Multi-Threading (or Linux dies)!
>
> As microprocessor architectures are switching from single-core to
dual-core
> and multi-core architectures (couple years), the operating-systems such as
> Linux must follow. The announcements from hardware makers such as Intel,
> AMD and Sun regarding their new soon to be released (within next 2 years)
> multi-core microprocessors is very revealing.
>
> The Linux kernel must undergo a deep overhaul if it does not want to fall
> into obsolescence. Linux must be updated to support massive
> multi-threading microprocessor technology. There is no way around it.
> Microsoft will surely update Windows but the Linux community seems slow to
> react. This technology will first appear in severs where Linux has a bit
of
> an edge. So Linux will soon fell the heat on this.
>
> I have included below an article from the Internet magazine The Inquirer
> that talks extensively about Sun's future multi-core design. Read it
> carefully. It's a rare to find this level of details. This should give
you
> an idea about what is coming in the near future.
> http://www.theinquirer.net/Default.aspx?article=19423
|