While we are trying applying oProfile
in our Linux system on board, which is kernel 2.6.5 and the processor is
PowerPC 440, we met a strange problem that all timer samples come from
kernel space (above 0xc0000000). All timer samples in an oProfile session,
no matter they are from any applications such as 'hello_world' or 'ls'
or 'find', are out of addresses above 0xc0000000.
We found PowerPC 440 is still not officially
supported by oProfile, so we can get only timer instead of hardware event.
But according to oProfile manual, we cannot do any configration for oProfile
in timer mode. We do not have unitmask for timer mode either, so we cannot
set any filter for samples from kernel/user mode, just as unitmask in event
mode to set sample filter.
We are hoping to get user mode samples
for profile analysis. Only kernel mode timer is not enough. Is there any
other locations we should do but we missed for timer mode configuration?
If there is any filter for address space, we have to remove it, but we
do not know. Anyone can point out where the root cause possibly lies? The
kernel is not compiled by our team so that I do not know very clear about
its config. Thank you very much.
China Systems and Technology Lab, IBM Shanghai
3rd Floor, No.78, Lane 887, Zu Chong Zhi Road, Zhangjiang High Tech Park,
Shanghai, 201203, China