dLux wrote:
>
> Hello!
>
> I need to measure the time spent in one process, and I need to do
> it as exact as possible (about 1us). 2.2.x kernel series, Pentium II
> proc.
>
> My first and not-yet-working solution:
>
> I declared 3 variables in the arch/i386/kernel/process.c:
>
> static pid_t ProcID;
> static unsigned long long int RunStart;
> static unsigned long long int Elapsed;
>
> ProcID is the process id, which needs to be profiled. Elapsed is
> the time commulated in the process running, RunStart is a temporary
> variable.
>
> I put some additional code to the beginning of the __switch_to in
> the arch/i386/kernel/process.c:
>
> if (prev->pid == ProcID) {
> Elapsed += rdtsc_return()-RunStart;
> } else if (next->pid == ProcID) {
> RunStart = rdtsc_return();
> };
>
> rdtsc_return() is a function, which returns the Pentium clock in
> long long int format.
>
> These code checks if the process we want to measure is on the
> schedule or not.
>
> After it I wanted to write a kernel module, which registered a
> file in the /proc, and it can set the ProcID via it, and get the
> "Elapsed" value from it.
> The problem is that I don't know how I use that variables.
>
> I tried this:
>
> extern pid_t ProcID;
> extern long long int Elapsed;
>
> But when I want to use my module, it prints:
>
> or2:/projects/boomerang/timer# insmod timermod.o
> timermod.o: unresolved symbol ProcID
> timermod.o: unresolved symbol Elapsed
>
> (The timermod.c originally based on the procfs.c file, which is
> included in some kernel howto.)
>
> The System.map file in the /usr/src/linux-2.2.13 contains that
> symbols:
>
> c021c8c0 b ProcID
> c021c8cc b Elapsed
>
> I copied the System.map into /boot/System.map-2.2.13,
> /lib/modules/2.2.13, but it doesn't help. Do you know how I can
> access those variables?
>
> Another question:
> -----------------
> Do you know a better and faster way to access that variables? May I
> make a device driver for it? Make a syscall? Please refer me to the
> URL when I can study these materials.
>
> Thanks for any help in advance,
>
the variable are defined as "static", so they're not visible
outside of the source file they're in. remove the "static" and
pick better names (since they will now be global). it will also
help to keep the types the same for both the definition and
the declaration ...
jan-simon.
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