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Groups > comp.os.linux.misc > #8298

Re: Wish to try Linux

From Jean-David Beyer <jeandavid8@verizon.net>
Newsgroups comp.os.linux.misc
Subject Re: Wish to try Linux
Date 2013-06-02 14:52 -0400
Organization NewsGuy - Unlimited Usenet $23.95
Message-ID <kog4a60757@news4.newsguy.com> (permalink)
References (11 earlier) <koecp302o35@news6.newsguy.com> <87sj1029pk.fsf@araminta.anjou.terraraq.org.uk> <kof8n802dnc@news7.newsguy.com> <_LWdnTPUWuFMtjbMnZ2dnUVZ8vydnZ2d@lyse.net> <kofluj$mfc$1@news.albasani.net>

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On 06/02/2013 10:47 AM, The Natural Philosopher wrote:
> On 02/06/13 12:26, David Brown wrote:
>> On 02/06/13 13:02, Jean-David Beyer wrote:
>>> On 06/02/2013 04:33 AM, Richard Kettlewell wrote:
>>>> Jean-David Beyer <jeandavid8@verizon.net> writes:
>>>>> In the distant past, a colleague and I had occasion to write an
>>>>> assembly-language level optimizer (mainly for C programs) for the
>>>>> SPARC
>>>>> RISC processor. We had already done one for the AT&T 32100 series
>>>>> processors (conventional architecture). I found doing that to be
>>>>> somewhat more difficult than for the normal processors such as Intel
>>>>> 80386 and the Motorola 68000 series of the same time. Delay slots,
>>>>> etc.
>>>>>
>>>>> But I did not find that they used any less memory for the
>>>>> instructions
>>>>> because any one instruction may have been smaller than for complex
>>>>> instruction set machines, but it took between 2 or 3 instructions to
>>>>> do the same thing as a single instruction on the more traditional
>>>>> machines.  Furthermore, you then had to do 2 to 3 instruction
>>>>> fetches,
>>>>> so they tended to run slower per computation even though any single
>>>>> instruction could run faster.
>>>>
>>>> Comparing a few libraries which we build across multiple platforms, I
>>>> find SPARC produces object code up to 1-50% bigger than x86, but x86
>>>> 20-30% bigger than PPC.  My conclusion is that you can’t reliably say
>>>> RISC ISAs produce either larger or smaller code than CISC, and
>>>> aren’t on
>>>> particularly solid ground seeking a comparison just between two
>>>> specific
>>>> ISAs - i.e. it can vary a fair bit depending on the specific code.
>>>>
>>>> (Stripped object code in all cases, mostly compiled C.)
>>>>
>>> My guess is that you are right. Where I worked, they also were
>>> trying to
>>> build a processor RISC chip oriented specifically to running compiled C
>>> programs. I do not know if they ever manufactured the chip or not,
>>> but I
>>> did get a copy of the instruction set. I do not know what they were
>>> anymore, but I do remember that this so-called RISC processor, that
>>> they
>>> were calling CRISP at the time, had more op-codes than any other
>>> machine
>>> I had ever seen, even the IBM 7094, Something like 350 op-codes. I was
>>> disgusted. If that is C REDUCED INSTRUCTION SET PROCESSOR, I do not
>>> know
>>> what they thought would be a complex instruction set machine. I know I
>>> never got asked to write an optimizer for it.
>>>
>>
>> It is a common misconception that a RISC architecture has a small
>> number of opcodes - i.e., the parsing is "Reduced" "Instruction-Set"
>> "Computer".  In fact, RISC means the /instructions/ are reduced, not
>> the /instruction set/ - it is "Reduced Instruction" "Set" "Computer".
>>
>> Thus a RISC architecture like the PPC has a very large number of
>> op-codes, but they are almost all "simple" and execute in a single
>> cycle rather than with loops, microcode, multiple steps, etc., as is
>> normal in CISC architectures.  Some instructions, like the bitfield
>> manipulations, are pretty complicated - but as they execute using
>> dedicated single-cycle logic, they are still classed as "simple".  Of
>> course, there are still some multi-cycle complex instructions,
>> especially for things like floating-point operations.  But most of
>> the op-codes are "simple".
>>
> And of course as anyone who has run FORTH will tell you, you can trade
> compactness of code for execution speed,  more or less at will. Its
> possible also to hunt through assembler code and find any pattern of
> more than half a dozen instructions, turn it into a subroutine and
> call it.. destroys pipelines of course.
>
Destroys pipelines, but can improve working set locality. It is a
tradeoff of course.

The optimizer I helped write had an "optimize for speed" and an
"optimize for space" option.
In optimize for speed, it would expand subroutines in-line (and it had
to be careful about recursive subroutines in many manifestations). But a
secondary benefit for expanding a subroutine inline is that it gave the
optimizer the opportunity to make much more extensive optimizations
because it had more information available.

I found writing optimizers a lot of fun, but realistically, since it
could easily take 18 months to make significant changes in an optimizer,
and test the functions, test the entire optimizer, the entire
compilation system, then build the UNIX kernel with all the
optimizations turned on and get it to keep working, and then send it to
system integration and system test, ....
Well in that amount of time, the speed of the processors doubled, and we
rarely got a 100% speed increase with optimizations except for the
benchmarks, so it was kind-of futile.

In a reasonable world, the optimizer would continue to work for the
faster processor, but they always made other little changes in the
processors so the optimzations would not work, and we had to do big
parts over again. Lots of fun for problem solving, but I somehow doubt
the computing world was actually improved much by our work.

Sigh!

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Thread

Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-09 20:09 +0100
  Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-09 15:25 -0400
    Re: Wish to try Linux Robert Heller <heller@deepsoft.com> - 2013-05-09 15:24 -0500
      Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-09 21:51 +0100
      Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-09 18:41 -0400
  Re: Wish to try Linux Dan Espen <despen@verizon.net> - 2013-05-09 15:28 -0400
    Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-10 16:48 +0100
  Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-09 20:48 +0100
    Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-09 16:45 -0400
      Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-09 23:50 +0100
        Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-10 07:41 -0400
          Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 13:01 +0100
            Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-10 08:49 -0400
              Re: Wish to try Linux Aragorn <stryder@telenet.be.invalid> - 2013-05-10 15:20 +0200
                Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-10 16:11 -0400
          Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-10 08:04 -0400
            Re: Wish to try Linux Bill Marcum <bill@nowhere.invalid> - 2013-05-16 07:58 -0400
          Re: Wish to try Linux Bill Marcum <bill@nowhere.invalid> - 2013-05-16 07:56 -0400
            Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-16 09:32 -0400
              Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-05-16 16:03 +0200
                Re: Wish to try Linux John Hasler <jhasler@newsguy.com> - 2013-05-16 09:27 -0500
                Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-16 10:53 -0400
                Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-16 15:30 +0100
                Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-16 10:52 -0400
              Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-16 15:30 +0100
              Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-16 16:14 -0400
                Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-16 17:23 -0400
    Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-05-09 23:49 +0000
      Re: Wish to try Linux Robert Heller <heller@deepsoft.com> - 2013-05-09 19:35 -0500
        Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 05:30 +0100
          Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-05-10 14:27 +0000
      Re: Wish to try Linux Michael Black <et472@ncf.ca> - 2013-05-09 22:13 -0400
    Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-10 16:50 +0100
      Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 17:19 +0100
        Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-15 16:27 +0100
          Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-15 16:34 +0000
            Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-15 17:46 +0100
              Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-15 18:15 +0000
                Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-15 19:32 +0100
                Re: Wish to try Linux Dan Espen <despen@verizon.net> - 2013-05-15 14:52 -0400
                Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-15 21:11 +0000
                Re: Wish to try Linux Robert Heller <heller@deepsoft.com> - 2013-05-15 13:54 -0500
                Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-16 01:01 -0400
                Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-05-16 10:52 +0200
                Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-16 08:25 -0400
                Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-16 18:56 +0000
                Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-16 20:33 +0100
                Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-16 19:35 +0000
                Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-16 20:43 +0100
                Re: Wish to try Linux bruce.sinclair@NOSPAMORELSEagresearch.NOTco.NOTnz (Bruce Sinclair) - 2013-05-19 23:33 +0000
                Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-16 16:16 -0400
          Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-15 17:44 +0100
            Re: Wish to try Linux Robert Heller <heller@deepsoft.com> - 2013-05-15 13:44 -0500
              Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-15 20:37 +0100
    Re: Wish to try Linux "Chris F.A. Johnson" <cfajohnson@gmail.com> - 2013-05-14 13:51 -0400
      Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-14 21:16 +0100
        Re: Wish to try Linux "Chris F.A. Johnson" <cfajohnson@gmail.com> - 2013-05-14 17:49 -0400
          Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-15 00:02 +0100
  Re: Wish to try Linux Robert Heller <heller@deepsoft.com> - 2013-05-09 15:03 -0500
    Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-23 14:09 +0100
      Re: Wish to try Linux Richard Kettlewell <rjk@greenend.org.uk> - 2013-05-23 14:38 +0100
        Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-23 16:33 +0100
          Re: Wish to try Linux John Hasler <jhasler@newsguy.com> - 2013-05-23 10:55 -0500
            Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-23 19:00 +0100
              Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-06-01 11:43 +0200
                Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-06-01 11:37 +0000
                Re: Wish to try Linux Balwinder S Dheeman <bsd.SANSPAM@anu.homelinux.net> - 2013-06-01 21:59 +0530
                Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-06-01 19:14 +0200
                Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-06-01 17:43 +0000
                Re: Wish to try Linux Michael Black <et472@ncf.ca> - 2013-06-01 19:33 -0400
                Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-06-02 02:37 +0200
                Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-06-01 23:05 -0400
                Re: Wish to try Linux Richard Kettlewell <rjk@greenend.org.uk> - 2013-06-02 09:33 +0100
                Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-06-02 07:02 -0400
                Re: Wish to try Linux David Brown <david.brown@removethis.hesbynett.no> - 2013-06-02 13:26 +0200
                Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-06-02 15:47 +0100
                Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-06-02 14:52 -0400
                Re: Wish to try Linux David Brown <david.brown@removethis.hesbynett.no> - 2013-06-02 13:32 +0200
          Re: Wish to try Linux Roger Blake <rogblake@iname.invalid> - 2013-05-23 17:09 +0000
            Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-23 19:06 +0100
            Re: Wish to try Linux Robert Riches <spamtrap42@jacob21819.net> - 2013-05-24 04:48 +0000
  Re: Wish to try Linux Bit Twister <BitTwister@mouse-potato.com> - 2013-05-09 20:03 +0000
  Re: Wish to try Linux unruh <unruh@invalid.ca> - 2013-05-09 20:19 +0000
    Re: Wish to try Linux bad sector <forgetski@postit_INVALID_.gov> - 2013-05-09 20:27 -0400
      Re: Wish to try Linux unruh <unruh@invalid.ca> - 2013-05-10 15:30 +0000
  Re: Wish to try Linux Stef <not@this.address.com> - 2013-05-10 03:05 +0000
    Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-05-10 14:35 +0000
      Re: Wish to try Linux Stef <not@this.address.com> - 2013-05-10 16:44 +0000
        Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-05-10 16:57 +0000
          Re: Wish to try Linux Stef <not@this.address.com> - 2013-05-11 03:59 +0000
            Re: Wish to try Linux Michael Black <et472@ncf.ca> - 2013-05-11 00:27 -0400
              Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-05-11 12:49 +0000
                Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-11 12:56 +0000
                Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-05-11 15:20 +0200
                Re: Wish to try Linux notbob <notbob@nothome.com> - 2013-05-11 14:14 +0000
                Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-11 10:30 -0400
                Re: Wish to try Linux  OOps Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-11 10:38 -0400
                Re: Wish to try Linux  OOps Robert Riches <spamtrap42@jacob21819.net> - 2013-05-12 04:37 +0000
                Re: Wish to try Linux Michael Black <et472@ncf.ca> - 2013-05-11 13:47 -0400
    Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-10 16:58 +0100
  Re: Wish to try Linux Aragorn <stryder@telenet.be.invalid> - 2013-05-10 06:53 +0200
    Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 07:26 +0100
      Re: Wish to try Linux Aragorn <stryder@telenet.be.invalid> - 2013-05-10 09:18 +0200
        Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 10:20 +0100
          Re: Wish to try Linux Aragorn <stryder@telenet.be.invalid> - 2013-05-10 11:40 +0200
      Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-10 07:44 -0400
        Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 13:00 +0100
          Re: Wish to try Linux Octothorpe <Octothorpe@invalid.com> - 2013-05-10 08:47 -0400
            Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 15:50 +0100
    Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-06-21 18:44 +0100
      Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-06-21 19:53 +0200
        Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-06-21 18:55 +0100
          Re: Wish to try Linux Aragorn <thorongil@telenet.be.invalid> - 2013-06-21 20:05 +0200
      Re: Wish to try Linux Richard Kettlewell <rjk@greenend.org.uk> - 2013-06-21 19:17 +0100
        Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-06-21 19:56 +0100
          Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-06-21 19:59 +0100
      Re: Wish to try Linux Antti Talsta <atalsta@gmail.com> - 2013-06-21 21:04 +0300
      Re: Wish to try Linux Michael Black <et472@ncf.ca> - 2013-06-21 17:51 -0400
      Re: Wish to try Linux Roger Blake <rogblake@iname.invalid> - 2013-06-22 01:48 +0000
      Re: Wish to try Linux Stan Bischof <stan@worldbadminton.com> - 2013-06-24 16:48 +0000
      Re: Wish to try Linux Stan Bischof <stan@worldbadminton.com> - 2013-06-24 16:56 +0000
  Re: Wish to try Linux DenverD <DenverD@invalid.dk> - 2013-05-10 09:17 +0200
  Re: Wish to try Linux lichtblitz <nospam@lichtblitz.invalid> - 2013-05-10 13:49 +0000
    Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-05-10 15:48 +0100
      Re: Wish to try Linux Robert Heller <heller@deepsoft.com> - 2013-05-10 11:21 -0500
        Re: Wish to try Linux lichtblitz <nospam@lichtblitz.invalid> - 2013-05-10 18:20 +0000
          Re: Wish to try Linux Richard Kettlewell <rjk@greenend.org.uk> - 2013-05-10 19:54 +0100
          Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-10 14:55 -0400
          Re: Wish to try Linux Aragorn <stryder@telenet.be.invalid> - 2013-05-11 05:40 +0200
            Re: Wish to try Linux Jean-David Beyer <jeandavid8@verizon.net> - 2013-05-11 07:55 -0400
    Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-10 16:07 +0000
      Re: Wish to try Linux lichtblitz <nospam@lichtblitz.invalid> - 2013-05-10 18:29 +0000
        Re: Wish to try Linux J G Miller <miller@yoyo.ORG> - 2013-05-10 19:48 +0000
  Re: Wish to try Linux David Hough <noone$$@llondel.org> - 2013-05-10 18:13 +0100
  Re: Wish to try Linux Dirk Weber <dma-weber@globe.lu> - 2013-05-10 19:09 +0200
  Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-05-14 19:01 +0100
    Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-06-23 22:55 +0100
      Re: Wish to try Linux The Natural Philosopher <tnp@invalid.invalid> - 2013-06-24 00:34 +0100
        Re: Wish to try Linux John Hasler <jhasler@newsguy.com> - 2013-06-23 19:23 -0500
          Re: Wish to try Linux David Brown <david.brown@removethis.hesbynett.no> - 2013-06-25 18:50 +0200
      Re: Wish to try Linux bruce.sinclair@NOSPAMORELSEagresearch.NOTco.NOTnz (Bruce Sinclair) - 2013-06-23 22:53 +0000
        Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-06-25 12:24 +0100
          Re: Wish to try Linux Michael Black <et472@ncf.ca> - 2013-06-25 12:28 -0400
          Re: Wish to try Linux bruce.sinclair@NOSPAMORELSEagresearch.NOTco.NOTnz (Bruce Sinclair) - 2013-06-25 23:11 +0000
      Re: Wish to try Linux John Hasler <jhasler@newsguy.com> - 2013-06-23 19:30 -0500
        Re: Wish to try Linux Ross Maloney <rmatycorp@iinet.net.au> - 2013-06-24 11:07 +0800
        Re: Wish to try Linux Peter Percival <peterxpercival@hotmail.com> - 2013-06-25 12:52 +0100

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