Re: [Emc-users] Fwd: Re: Comment on EMC installation

[Ray H. <re...@up...>]

Hi Dave.

My understanding of all of these issues is at best theoretical and murky.  My 
thinking comes from reading some of the rt and rtai posts by Yodaikin and the 
other real-time folk.  When I wrote that, I was thinking of some of the hard 
wired work arounds that have been done for buggy silicon.  At worst these 
kinds of problems add jitter to our steper pulse train.

The newest intel stuff can be difficult and I have not tried to compile for 
any of these.  The 8?? chipsets have been causing problems with BDI because 
they were developed after most of the device drivers and x window versions 
available in those distributions.  For my money I'd choose something like the 
$219.00, 1.1 GHz Lindows pc that TigerDirect is offering right now. (no 
connection with them)  Yes it is old technology and the first thing I'd do is 
sacrefice the newer Lindows distro for BDI.  It sounds like one giant leap 
backwards but at least I'd have a known, and very fast, system for making 
chips.

I'm sure that the Linux community is working on threading issues.  I've heard 
good things about SuSE and some of the pioneering hardware work they are 
about.  I find it fascinating that their Linux  release for the 64 bit AMD 
chip was the only OS available when the chip was released.  I also know that 
Linus and the core developers have been working on several schemes and that 
some of this work is available in the 2.5++ versions of the kernel.  I have 
no urge to get that far out on the bleeding edge.

I am certain also that the EMC community will be caused to make changes to 
the way we do real time by these new technologies.  We have had a recent, 
significant discussion with another software development group about user 
space vs kernel space real-time.  While they have much to offer, our feeling 
was that we could not sacrefice hard real time at least as we do it now.

None of this should be taken as saying that Ray Henry is into old and not 
enouraging new.  I am excited to hear about people working to apply the 
latest and greatest stuff.  If I can help, I will in any way that I can.  EMC 
has a real advantage in that it can run on the cast off hardware from those 
other OS's but we should not be content to call that advantage enough.

Hope this helps.

Ray


On Sunday 15 June 2003 12:30 pm, you wrote:
> HI Ray;
>
> Important questions regarding the paragraph below.
>
> Are there specific issues with hardware based scheduling?    I'm
> assuming this is a reference to Intels newest processors and the Multi
> Threading features they have.    If so should one stay away from such
> hardware?    Since I'm shopping around for emc hardware, understanding
> this issue in relation to the latest Intel hardware is important.
>
> Also while I do not like RedHats approach at all to the new threading
> model, I do hope that everyone realizes that the Linux community will
> have to change threading models at some time in the future.   Of course
> we could stick with older Kernels for a very long time if emc required.
>
> Thanks
> dave
>
>
> Ray Henry wrote:
>
> From: Ray Henry <re...@up...>
>
> >The RedHat based threading competes with RT and RTAI for the attention of
> > the processor as do some of the hardware based scheduling that we are
> > seeing from chip and board makers.  Our dependence upon hard-real-time
> > makes a good working system a bit more difficult the farther into these
> > things those we move.
> >
> >
> >Snipped<<<<<<<<<<<<<<<<<<<<<<,
>
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