28 Jul
2014
28 Jul
'14
2:05 p.m.
On 28 July 2014 14:45, Kugan kugan.vivekanandarajah@linaro.org wrote:
It could be the kernel version we use in lab. AFAIK, Charles had some luck profiling with perf on newer kernel. I am not sure about the version though.
I have seen working performance counters on 3.15-rc8. The versions of the kernel we have on our aarch64 lab hardware have kernel oopses when hardware counters are used. On Juno, the 3.14 linaro kernel seems not to provide access to the performance counters.
Some care needs to be taken with perf reports on both arm/aarch64, as they are sometimes have bogus addresses in the profile. (sometimes large amounts of time can be attributed to anonymous hex addresses, do not ignore these. I have a workaround script)