Re: [RFC] ARM binutils feature churn causing kernel problems

Paulo Marques
2004-10-08T16:37:15Z

Russell King wrote:
> On Mon, Sep 27, 2004 at 09:03:05PM +0100, Russell King wrote:
>
>>The ARM binutils seems to be in a problematical state at the moment.
>>It has recently had a "bug" fixed where ARM specific "mapping symbols"
>>were not generated in ELF objects. These "mapping symbols" have names
>>such as "$a" and "$d".
>
>
> Ok, another tool which is affected by this is procps:
>
> $ ps alx
> Warning: /boot/System.map-2.6.9-rc3 not parseable as a System.map
> Warning: /boot/System.map not parseable as a System.map
> Warning: /usr/src/linux/System.map has an incorrect kernel version.
> F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY TIME COMMAND
> 4 0 1 0 16 0 1244 508 do_sel S ? 0:01 init [3]

ps is reading System.map probably because reading /proc/<pid>/wchan
directly was very slow. It used to take an average of 1.3ms (on a P4
2.8GHz) and now it takes less than 0.5us (that is miliseconds and
microseconds!)

If this is the case, then after the changes to kallsyms go in, procps
could start using wchan directly and avoid reading the System.map
altogether.

I'm adding Albert Cahalan to this list since he should know a little
more about this :)

--
Paulo Marques - www.grupopie.com

To err is human, but to really foul things up requires a computer.
Farmers' Almanac, 1978