Am 25.02.2013 um 19:02 schrieb Tom Easterday:
> On Feb 25, 2013, at 12:21 PM, Michael Haberler <[email protected]> wrote:
>> try strace ...
>
>
> Output from "strace -o filename halcmd -s show pin wcomp.3.max" is here:
> http://bgp.nu/~tom/pub/1204.trace.txt 12.04/Xenomai on Atom 2700
> http://bgp.nu/~tom/pub/1004.trace.txt 10.04/rtai on Atom 2500
>
> Not sure what I should be looking for in here but I see some "No such file or
> directory" errors in the 12.04 version:
'man strace' will tell you that system call timing can by had by the -c and -r
switches, for instance:
strace -r halcmd show pin
looking at the system call timestamps should give a clue where time is spent
since it's for sure not the application code per se, which is trivial in this
case
You will _always_ see "No such file or directory" 'errors' and that is not an
error you need to be concerned about - that is just the dynamic loader trying
to open shared libraries along the loader path, which you can tell from the
pathnames
What is obvious is that your 12.04 version tries many more shared library
directories that the 10.04 version. However, part of that is a consequence of
the run-in-place build, or a different dynamic loader behaviour, and has
nothing to do with the application code:
typical example: open("/home/tom/linuxcnc-rtos/lib/libreadline.so.6",
O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
-----------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is a system-wide shared library, but due to the run-in-place build it
tries the local lib directory first, before succeeding on the one installed in
/lib:
open("/lib/i386-linux-gnu/libreadline.so.6", O_RDONLY|O_CLOEXEC) = 3
Summary: to make figures comparable, you need comparable build options.
---
That said: what exactly is the tuning effort about? There are various ways to
access pins, and I think pretty much all of them would be orders of magnitude
faster than 'halcmd show pin x' ?
- Michael
> -Tom
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