Andi Kleen wrote:
On a working kernel on an Opteron, we have normally 4 directories
in /dev/oprofile :
# ls -ld /dev/oprofile/?
drwxr-xr-x 1 root root 0 15. Nov 12:38 /dev/oprofile/0
drwxr-xr-x 1 root root 0 15. Nov 12:38 /dev/oprofile/1
drwxr-xr-x 1 root root 0 15. Nov 12:38 /dev/oprofile/2
drwxr-xr-x 1 root root 0 15. Nov 12:38 /dev/oprofile/3
With linux-2.6.19-rc5, the first one (0) is missing and we get 1,2,3
That's because 0 was never available. It is used by the NMI watchdog.
The new kernel doesn't give it to oprofile anymore.
Maybe the 'bug' is in oprofile tools, that currently expect to find '0'
Yes, it's likely a user space issue.
-Andi
OProfile has a simplistic view of the performance monitoring hardware. The
routines in libop/op_alloc_counter.c determine what set of performance registers
is available from the processor in use. There is no check to see what registers
are actually available in the /dev/oprofile directory.
opcontrol executes ophelp to determine which specific counters to count which
events. The function map_event_to_counter() in libop/op_alloc_counter.c does the
actual selection. It seems what is needed is for map_event_to_counter() to check
to see which counters are available and mark the others as unavailable.
-Will
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