Reproduction micros

[Guy Sotomayor Jr]

> On Jul 21, 2016, at 8:55 PM, ben <bfranchuk at jetnet.ab.ca> wrote:
> 
> On 7/21/2016 9:34 PM, Guy Sotomayor Jr wrote:
>> 
>>> On Jul 21, 2016, at 6:53 PM, ben <bfranchuk at jetnet.ab.ca> wrote:
>>> 
>>> On 7/20/2016 10:42 AM, Pete Turnbull wrote:
>>>> On 20/07/2016 16:44, Paul Koning wrote:
>>>> 
>>>>> It is true that a few RISC architectures are not very scrutable.
>>>>> Itanium is a notorious example, as are some VLIW machines.  But many
>>>>> RISC machines are much more sane.  MIPS and ARM certainly are no
>>>>> problem for any competent assembly language programmer.
>>>> 
>>>> Indeed.  I've written a modest amount of assembly language code for
>>>> MIPS, and a bit more for ARM, and I didn't find either at all
>>>> inscrutable.  Yes, be aware of pipelining and branches and so on, but
>>>> it's not hard.
>>> 
>>> But alas , they seem to change cache and pipeline with every cpu
>>> starting with 386. How can one write effective programs for large
>>> data memory access, with out this knowledge?
>> 
>> You read the Intel Optimization Guide.
>> 
>> http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-optimization-manual.html
>> 
>> TTFN - Guy
> 
> A read and cuss item I see. Thank you, but it seems it is still big $$$
> for good compiler to follow the ever changing rules.

And yet they do.  Processors are getting more and more complex in order
to deliver power/performance improvements.  Larger caches with more ways,
deeper/wider pipes, more execution slots, number of rename registers, etc.

What do you expect?  TNSTAAFL if you want to extract every last cycle of
performance out of a particular uArch.  The good news is that most of the
time the uArch improvements work reasonably well with relatively non-specific
optimizations.

TTFN - Guy