Re: Ada versus Java - Tasking

[ohk@ultra.tfdt-o.nta.no (Ole-Hjalmar Kristensen FOU.TD/DELAB)]

In article <JSA.97Jan20164909@alexandria> jsa@alexandria (Jon S Anthony) writes:

   In article <1997Jan19.122511.1@eisner> kilgallen@eisner.decus.org (Larry Kilgallen) writes:

   > Operating system developers have a much better chance to make the
   > scheduling interact with the hardware properly, so I think the better
   > choices are:
   > 
   > 	1) Rely on OS threading support, and wait for improvements.
   > 
   > 	2) Lobby the operating system provider for better support,
   > 	   using all methods available, including examples of other
   > 	   operating systems which do it better, either on the same
   > 	   hardware or some other hardware.

   Abosolutely.  If you happen to need something better than this you
   probably should not be using typical run of the mill OSs in the first
   place.

   /Jon
   -- 
   Jon Anthony
   Organon Motives, Inc.
   Belmont, MA 02178
   617.484.3383
   jsa@organon.com

Many applications are typically required to both run on standard OSs,
have good performance, and be portable. DB and TP systems are obvious
examples. Of course, you can just avoid using any mechanisms which are too
slow, but that may rule out using mecanisms which otherwise could be
used to great advantage. With transaction response times in the range
of typically 1..10 milliseconds, you don't have time for too many
context switches, although I do not think using Ada tasks to represent
transactions would be prohibitively costly. The greatest resource hog
in the system I'm working on (written in C++, btw) is undoubtedly the
network layer, which accounts for more than 1/3 of the CPU time...