On Mon, Jul 09, 2018 at 07:15:22AM -0700, [email protected] wrote: > From: Kan Liang <[email protected]> > > Perf record will error out if both --delay and LBR are applied. > For example: > perf record -D 1000 -a -e cycles -j any -- sleep 2 > Error: > dummy:HG: PMU Hardware doesn't support sampling/overflow-interrupts. > Try 'perf stat' > > A dummy event is added implicitly for initial delay, which has the same > configurations as real sampling events. The dummy event is a software > event. If LBR is configured, perf must error out. > > The dummy event only be used to track PERF_RECORD_MMAP while perf waits > for the initial delay to enable the real events. The BRANCH_STACK bit > can be safely cleared for the dummy event. > > After applying the patch: > perf record -D 1000 -a -e cycles -j any -- sleep 2 > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 1.054 MB perf.data (828 samples) ] > > Reported-by: Pandey, Sunil K <[email protected]> > Signed-off-by: Kan Liang <[email protected]>
Acked-by: Jiri Olsa <[email protected]> thanks, jirka
