Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Programming > Java > Java processors

Reply
Thread Tools

Java processors

 
 
Jan Burse
Guest
Posts: n/a
 
      07-06-2012
Roedy Green schrieb:
> On Thu, 05 Jul 2012 13:02:44 -0600, Jim Janney
> <(E-Mail Removed)> wrote, quoted or indirectly quoted
> someone who said :
>
>> Back in the day Niklaus Wirth had a system that was optimised for
>> running Modula-2, with its own processor and operating system written in
>> Modula-2. I don't remember now what it was called.

> Lilith.
> see
> http://www.ethistory.ethz.ch/rueckbl...popupfriendly/
>


But it was not the only machine used in teaching
those days.

In the vincinity of the ETH one could find in
the mid 80's:

- CDC via Batch
- VAX via Tektronic
- Apple ][
- Lilith
- Sun 3/60
- Cray-2 via Batch
- What else?

And in personal use:

- MZ 80K
- Atari ST
- Amiga 500
- Macintosh
- What else?

The fun thing was moving code from one platform to
another. But it didn't happen that often.

Corresponding concern only arised more deeply 10
years later.

Bye
 
Reply With Quote
 
 
 
 
Lew
Guest
Posts: n/a
 
      07-06-2012
Gene Wirchenko wrote:
> Roedy Green wrote:
>>Eric Sosman wrote, quoted or indirectly quoted someone who said :
>>> If you just dove in and started
>>> interpreting you might be running more slowly, but you'd have a
>>> head start

>>
>> That is just what JITs do. It is only after a while they have gathered
>> some stats to they decide which classes to turn to machine code. The
>> astounding thing is they stop the interpreter in mid flight executing
>> a method, and replace it with machine code and restart it. That to me
>> is far more impressive than walking on water.


They don't do that exactly. There's no restart.

<http://www.oracle.com/technetwork/java/hotspotfaq-138619.html#compiler_warmup>

> Do you have a cite [sic] for that? Restarting a method could be messy.


This was in the links I provided upthread.

> Imagine if files are opened, other objects created, etc.
>
> I suspect that it might be as prosaic as a method execution times
> counter reaching a threshold value triggering the conversion.


Also cited upthread. I don't know that it's method-by-method; I
think HotSpot optimizes at finer granularity than that. The cited
reference refers to optimizing "loops".

But it's far from prosaic. The HotSpot compiler (not to be confused with
other JIT compilers) can switch to native-compiled code mid-execution
while the interpreted code is running. Given that the compiler is
aware of run-time circumstances, I don't know that it would need to
have trouble with file handles and the sorts of things you mention.

--
Lew
 
Reply With Quote
 
 
 
 
Martin Gregorie
Guest
Posts: n/a
 
      07-06-2012
On Fri, 06 Jul 2012 13:53:21 -0700, Roedy Green wrote:

> The underlying hardware had only 24 bits addressing, but it was bit
> addressable. That let you address bytes with 21 bits, a mere 2
> megabytes.Yet that little machine pumped out transactions like you would
> not believe. It used memory very cleverly dynamically balancing system,
> app, database, disk cache.
>

As I'm certain you know, driving 24x80 green screens allowed machines to
use very much less memory than today's hardware with its memory-hungry
high-resolution graphics. The BBC's pair of 2966s could each run 10-12
online IDMSX-based systems, which together were accessed by 300-400
terminals, yet each machine did all that with 16 MB of RAM.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
 
Reply With Quote
 
Silvio Bierman
Guest
Posts: n/a
 
      07-06-2012
On 07/06/2012 11:04 PM, Jan Burse wrote:

> - CDC via Batch
> - VAX via Tektronic
> - Apple ][
> - Lilith
> - Sun 3/60
> - Cray-2 via Batch
> - What else?


I used to love working on a DEC-PDP11 running Unix. A great machine and
it had a Modula 2 compiler to boot.

>
> And in personal use:
>
> - MZ 80K
> - Atari ST


That one was awesome. I still have mine collecting dust in the attic.

Back then (somewhere around 1986) I built a preemptive (timer interrupt
based) threading library for it. It allowed any number of C functions to
be run "in parallel" with each other and the main thread, only limited
by the available memory to be allocated as thread stacks.

Built quite some cool games with that.


Ah, the good old days...

Silvio
 
Reply With Quote
 
Eric Sosman
Guest
Posts: n/a
 
      07-06-2012
On 7/6/2012 5:18 PM, Martin Gregorie wrote:
> On Fri, 06 Jul 2012 13:53:21 -0700, Roedy Green wrote:
>
>> The underlying hardware had only 24 bits addressing, but it was bit
>> addressable. That let you address bytes with 21 bits, a mere 2
>> megabytes.Yet that little machine pumped out transactions like you would
>> not believe. It used memory very cleverly dynamically balancing system,
>> app, database, disk cache.
>>

> As I'm certain you know, driving 24x80 green screens allowed machines to
> use very much less memory than today's hardware with its memory-hungry
> high-resolution graphics. The BBC's pair of 2966s could each run 10-12
> online IDMSX-based systems, which together were accessed by 300-400
> terminals, yet each machine did all that with 16 MB of RAM.


"MEGAbytes? Looxurry. Moi 'ole college campus 'ad a grand
total of 128 KILObytes,[*] an' we wuz glad to 'ave it, we wuz.
But yew troi tellin' the kids nawadays ..."
[*] A couple decades ago it suddenly dawned on me that my
rather bare-bones video card had sixteen times the memory of my
college's mainframe. But yew troi tellin' the kids nawadays ...

--
Eric Sosman
http://www.velocityreviews.com/forums/(E-Mail Removed)d


 
Reply With Quote
 
Martin Gregorie
Guest
Posts: n/a
 
      07-06-2012
On Fri, 06 Jul 2012 18:17:49 -0400, Eric Sosman wrote:

> On 7/6/2012 5:18 PM, Martin Gregorie wrote:
>> On Fri, 06 Jul 2012 13:53:21 -0700, Roedy Green wrote:
>>
>>> The underlying hardware had only 24 bits addressing, but it was bit
>>> addressable. That let you address bytes with 21 bits, a mere 2
>>> megabytes.Yet that little machine pumped out transactions like you
>>> would not believe. It used memory very cleverly dynamically balancing
>>> system,
>>> app, database, disk cache.
>>>

>> As I'm certain you know, driving 24x80 green screens allowed machines
>> to use very much less memory than today's hardware with its
>> memory-hungry high-resolution graphics. The BBC's pair of 2966s could
>> each run 10-12 online IDMSX-based systems, which together were accessed
>> by 300-400 terminals, yet each machine did all that with 16 MB of RAM.

>
> "MEGAbytes? Looxurry. Moi 'ole college campus 'ad a grand
> total of 128 KILObytes,[*] an' we wuz glad to 'ave it, we wuz. But yew
> troi tellin' the kids nawadays ..."
>
>[*] A couple decades ago it suddenly dawned on me that my
> rather bare-bones video card had sixteen times the memory of my
> college's mainframe. But yew troi tellin' the kids nawadays ...


I wuz IMPRESSD by awl thet MEMORY in the 2966.

The biggest 1900 I ever used, a 1904S, had 256 Kwords of core memory
(24bit words). The one that taught me how to tune George 3 was a 1903S
with 32 Kwords of core memory - the equivalent of either 96 kB (counting
bits) or 128 KB (counting characters). The 1900 packed 4 6-bit ISO
characters into a word.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
 
Reply With Quote
 
Roedy Green
Guest
Posts: n/a
 
      07-07-2012
On Fri, 06 Jul 2012 13:50:17 -0700, Gene Wirchenko <(E-Mail Removed)>
wrote, quoted or indirectly quoted someone who said :

> Do you have a cite for that? Restarting a method could be messy.
>Imagine if files are opened, other objects created, etc.


It was probably at a lecture at Java One or at the Colorado software
conference. I got to ask Bill Joy a number of questions. It might
have been that day.
--
Roedy Green Canadian Mind Products
http://mindprod.com
Why do so many operating systems refuse to define a standard
temporary file marking mechanism? It could be a reserved lead character
such as the ~ or a reserved extension such as .tmp.
It could be a file attribute bit. Because they refuse, there is no
fool-proof way to scan a disk for orphaned temporary files and delete them.
Further, you can't tell where the orhaned files ame from.
This means the hard disks gradually fill up with garbage.

 
Reply With Quote
 
Roedy Green
Guest
Posts: n/a
 
      07-07-2012
On Fri, 6 Jul 2012 14:17:40 -0700 (PDT), Lew <(E-Mail Removed)>
wrote, quoted or indirectly quoted someone who said :

>
>They don't do that exactly. There's no restart.
>
><http://www.oracle.com/technetwork/java/hotspotfaq-138619.html#compiler_warmup>


" HotSpot contains On Stack Replacement technology which will compile
a running (interpreted) method and replace it while it is still
running in a loop. No need to waste your applications time warming up
seemingly infinite (or very long running) loops in order to get better
application performance."

It thus stops it is mid flight, possibly half way through a loop,
writes machine code, creates the equivalent state/register, and picks
up where it left off (what I ambiguously called restarting) but
running machine code. I can hardly believe this is possible,
especially when you think about all the optimisations on the machine
code.
--
Roedy Green Canadian Mind Products
http://mindprod.com
Why do so many operating systems refuse to define a standard
temporary file marking mechanism? It could be a reserved lead character
such as the ~ or a reserved extension such as .tmp.
It could be a file attribute bit. Because they refuse, there is no
fool-proof way to scan a disk for orphaned temporary files and delete them.
Further, you can't tell where the orhaned files ame from.
This means the hard disks gradually fill up with garbage.

 
Reply With Quote
 
Roedy Green
Guest
Posts: n/a
 
      07-07-2012
On Fri, 06 Jul 2012 18:17:49 -0400, Eric Sosman
<(E-Mail Removed)> wrote, quoted or indirectly quoted
someone who said :

> "MEGAbytes? Looxurry. Moi 'ole college campus 'ad a grand
>total of 128 KILObytes,[*] an' we wuz glad to 'ave it, we wuz.
>But yew troi tellin' the kids nawadays ..."


Univac made a unit record handling computer with 16K. Yet we had
threads in the thing and look-ahead i/o. Someday people won't believe
this. A beast like this ran the Vancouver Stock exchange.

--
Roedy Green Canadian Mind Products
http://mindprod.com
Why do so many operating systems refuse to define a standard
temporary file marking mechanism? It could be a reserved lead character
such as the ~ or a reserved extension such as .tmp.
It could be a file attribute bit. Because they refuse, there is no
fool-proof way to scan a disk for orphaned temporary files and delete them.
Further, you can't tell where the orhaned files ame from.
This means the hard disks gradually fill up with garbage.

 
Reply With Quote
 
Roedy Green
Guest
Posts: n/a
 
      07-07-2012
On Sat, 07 Jul 2012 00:13:44 +0200, Silvio Bierman <(E-Mail Removed)>
wrote, quoted or indirectly quoted someone who said :

>I used to love working on a DEC-PDP11 running Unix. A great machine and
>it had a Modula 2 compiler to boot.


The magic for me was the OS that did not crash several times a day. I
loved writing assembler for it. It was so logical. I think of C as a
high level assembler for it.

One of the most fun machines was the MINC with RT-11. It has all
kinds of real world interface i/o boards in it. I used it to control
a complicated solar energy experiment.

Is DEC/VAX still around?
--
Roedy Green Canadian Mind Products
http://mindprod.com
Why do so many operating systems refuse to define a standard
temporary file marking mechanism? It could be a reserved lead character
such as the ~ or a reserved extension such as .tmp.
It could be a file attribute bit. Because they refuse, there is no
fool-proof way to scan a disk for orphaned temporary files and delete them.
Further, you can't tell where the orhaned files ame from.
This means the hard disks gradually fill up with garbage.

 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
looking for performance statistics (native JAVA processors) noone Java 1 03-05-2006 08:04 PM
Java Application using Multi-Processors rprabhakaran@gmail.com Java 2 02-11-2006 04:30 AM
Java slow on Xeon processors ? Michael Kreitmann Java 11 05-25-2004 03:25 AM
Java servlets and multiple processors Bura Tino Java 7 04-16-2004 07:51 AM
Java & Intel Xeon Processors Mike Java 2 10-22-2003 07:40 PM



Advertisments