perf hists: Do not skip elided fields when processing samples
If user gives a filter, perf marks the corresponding column elided and
omits the output. But it should process and aggregates samples using
the field, otherwise samples will be aggregated as if the column was not
there resulted in incorrect output.
For example, I'd like to set a filter on native_write_msr_safe. The
original overhead of the function is negligible.
$ perf report | grep native_write_msr_safe
0.00% swapper [kernel.vmlinux] native_write_msr_safe
0.00% perf [kernel.vmlinux] native_write_msr_safe
However adding -S option gives different output.
$ perf report -S native_write_msr_safe --percentage absolute | \
> grep -e swapper -e perf
51.47% swapper [kernel.vmlinux]
4.14% perf [kernel.vmlinux]
Since it aggregated samples using comm and dso only. In fact, the above
values are same when it sorts with -s comm,dso.
$ perf report -s comm,dso | grep -e swapper -e perf
51.47% swapper [kernel.vmlinux]
4.14% perf [kernel.vmlinux]
This resulted in TUI failure with -ERANGE since it tries to increase
sample hit count for annotation with wrong symbols due to incorrect
aggregation.
This patch fixes it not to skip elided fields when comparing samples in
order to insert them to the hists.
Commiter note:
After the patch, with a different workloads:
# perf report --show-total-period -S native_write_msr_safe --stdio
#
# symbol: native_write_msr_safe
#
# Samples: 455 of event 'cycles:pp'
# Event count (approx.): 134787489
#
# Overhead Period Command Shared Object
# ........ ...... ............... ................
#
0.22% 293081 qemu-system-x86 [vmlinux]
0.19% 255914 swapper [vmlinux]
0.00% 2054 Timer [vmlinux]
0.00% 1021 firefox [vmlinux]
0.00% 2 perf [vmlinux]
# perf report --show-total-period | grep native_write_msr_safe
Failed to open /tmp/perf-14838.map, continuing without symbols
0.22% 293081 qemu-system-x86 [vmlinux] [k] native_write_msr_safe
0.19% 255914 swapper [vmlinux] [k] native_write_msr_safe
0.00% 2054 Timer [vmlinux] [k] native_write_msr_safe
0.00% 1021 firefox [vmlinux] [k] native_write_msr_safe
0.00% 2 perf [vmlinux] [k] native_write_msr_safe
#
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1448645559-31167-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
1 file changed