Help on difference of running on varius x86 with linux

Help on difference of running on varius x86 with linux

[Alessio Terpin]

hi ML

I'm  Alessio Terpin a student of Physic of the University of Trieste
(Italy)
for my thesis i wrote down C code using as tool for compiling the gcc
on Red Hat  6.1 Linux platform

The hardware that i have used is

P    200  64M
PMMX 233  128M
K6-2 400  128M

Profiling my code on this platform i have notice
that the same compiled file with Optimization level
machine independent -O1 -O2 -O3
present difference in the cpu consume of the varies function
so i have thought that this depend from the different architecture
of the CPU. It's right or there is some things that i don't have
see. In this case i think that the machine code is for 386

Another question when i use CPU optimization, i have used the same
that are used for compile the kernel what happen ?
Can give suggest where find this info

Thanks in Advance for all help can give me

P.S. Sorry for my English :-)

--
Saluti da Alessio Terpin

|---------------------------------------|
| Hello World!                          |
| The most difficult things to do ! K&R |
|---------------------------------------|

Help on difference of running on varius x86 with linux

[Alessio Terpin]

hi ML

I'm  Alessio Terpin a student of Physic of the University of Trieste
(Italy)
for my thesis i wrote down C code using as tool for compiling the gcc
on Red Hat  6.1 Linux platform

The hardware that i have used is

P    200  64M
PMMX 233  128M
K6-2 400  128M

Profiling my code on this platform i have notice
that the same compiled file with Optimization level
machine independent -O1 -O2 -O3
present difference in the cpu consume of the varies function
so i have thought that this depend from the different architecture
of the CPU. It's right or there is some things that i don't have
see. In this case i think that the machine code is for 386

Another question when i use CPU optimization, i have used the same
that are used for compile the kernel what happen ?
Can give suggest where find this info

Thanks in Advance for all help can give me

P.S. Sorry for my English :-)

--
Saluti da Alessio Terpin

|---------------------------------------|
| Hello World!                          |
| The most difficult things to do ! K&R |
|---------------------------------------|

Re: Help on difference of running on varius x86 with linux

[Martin v. Loewis]

> It's right or there is some things that i don't have see.

It is entirely possible that the execution speed of a certain code
varies from processor to processor. Some instructions behave better on
some processor, and different ones on another. Still, the -O options
only perform processor-independent optimizations, such as function
inlining.

> Another question when i use CPU optimization, i have used the same
> that are used for compile the kernel what happen ?
> Can give suggest where find this info

You can find the documentation of all command line flags in the gcc
manual. You can find the gcc manual by invoking 'info' on your system.

Regards,
Martin