linux-kernel - [BUG] perf report: garbage output with event grouping

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Date:	Wed, 26 Jun 2013 10:42:49 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung.kim@....com>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	David Ahern <dsahern@...il.com>
Subject: [BUG] perf report: garbage output with event grouping

Hi,


$ perf record -e 'cpi{cycles,instructions}' noploop 5

$ perf report --stdio --group
# group: ^P^Q<A0>\{cycles,instructions}
# ========
#
# Samples: 39K of event '^P^Q<A0>\ { cycles, instructions }'
# Event count (approx.): 37782563692
#
#         Overhead  Command      Shared Object                       Symbol
# ................  .......  .................  ...........................
#
    99.91%  99.98%  noploop  noploop            [.] main
     0.06%   -nan%  noploop  [kernel.kallsyms]  [k] read_hpet
     0.01%   0.01%  noploop  [kernel.kallsyms]  [k] __acct_update_integrals
     0.01%   -nan%  noploop  [kernel.kallsyms]  [k] raise_softirq
     0.01%   -nan%  noploop  [kernel.kallsyms]  [k] apic_timer_interrupt
     0.01%   -nan%  noploop  [kernel.kallsyms]  [k] __do_softirq
     0.01%   -nan%  noploop  [kernel.kallsyms]  [k] common_interrupt
     0.00%   0.00%  noploop  [kernel.kallsyms]  [k] intel_pmu_enable_all
     0.00%   0.01%  noploop  [kernel.kallsyms]  [k] cpuacct_account_field
     0.00%   0.01%  noploop  [kernel.kallsyms]  [k] __local_bh_enable


1. The group name is garbage if not anonymous group.
2. arithmetic error in the overhead columns leading to NaN.
3. I assume the Overhead column order is the group event order. Is that right?
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