on 5/9/00 16:39, Pennell, David at DPennell at quallaby.com wrote:

>> Someone wrote a slick program which sorted other programs so
>> that operands or the next instruction were just coming around
>> the drum when they were needed. This required rebuilding the
>> object code, scattering it all around the drum, and making it
>> great fun to debug, but it sure did help execution!
> 
> I read an interesting paper a year or so ago on the impact of poor
> I-cache coherency on modern processors.  The authors used a tool
> called "coord" to reorder a Unix TCP/IP stack to minimize cache
> misses.  They also saw a big performance boost.  I guess it just
> proves that there really isn't anything new.
> 
> -david
> 
> Thanks - some of you guys are making me feel young.  I wrote
> my first FORTRAN in '72 on a CDC 6600 - 60 bit words, 6 bit
> characters and all.  WHO NEEDS LOWER CASE ANYWAY?
> 

Well that's not too odd, as an on topic info item I attempted to resort the
globals in Squeak based on usage to see if d-cache concurrency would
improve. To do this I changed the slang engine to extrude all globals in a
structure in some form of sorted order. The first problem was how do you
measure and if you sling a few megabit bitplanes around you somewhat destroy
any value for the work that was involved with fiddling with d-cache usage.
Sorry I couldn't seem or measure any difference, but perhaps the thought of
doing it dates me somehow.


Yes someday I'll post  my slang engine changes, but beware this requires
code changes for platform specific implementation since most of them use
globals directly versus asking the VM to get/put values. I'd suggest people
do in fact use a mutator/accessor function to tangle with VM values, versus
assuming that they can get direct access to them by linking in.

Of course I do see that by using Tim's Plugable VM, most of these issues
disappear since you're not part of the VM.


--
===========================================================================
John M. McIntosh <johnmci at smalltalkconsulting.com> 1-800-477-2659
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
===========================================================================
Custom Macintosh programming & various Smalltalk dialects
PGP Key: DSS/Diff/46FC3BE6
Fingerprint=B22F 7D67 92B7 5D52 72D7  E94A EE69 2D21 46FC 3BE6
===========================================================================