From: Jin Yao <yao.jin@linux.intel.com>
To: acme@kernel.org, jolsa@kernel.org, peterz@infradead.org,
mingo@redhat.com, alexander.shishkin@linux.intel.com
Cc: Linux-kernel@vger.kernel.org, ak@linux.intel.com,
kan.liang@intel.com, yao.jin@intel.com,
Jin Yao <yao.jin@linux.intel.com>
Subject: [PATCH] perf evsel: Get group fd from CPU0 for system wide event
Date: Thu, 30 Apr 2020 09:34:51 +0800 [thread overview]
Message-ID: <20200430013451.17196-1-yao.jin@linux.intel.com> (raw)
A metric may consist of system wide event and non system-wide event.
The event group leader may be the system wide event.
For example, the metric "C2_Pkg_Residency" consists of
"cstate_pkg/c2-residency" and "msr/tsc". The former counts on the first
CPU of socket (tagged system-wide) and the latter is per CPU.
But "C2_Pkg_Residency" hits assertion failure on cascadelakex.
# perf stat -M "C2_Pkg_Residency" -a -- sleep 1
perf: util/evsel.c:1464: get_group_fd: Assertion `!(fd == -1)' failed.
Aborted
get_group_fd(evsel, cpu, thread)
{
leader = evsel->leader;
fd = FD(leader, cpu, thread);
BUG_ON(fd == -1);
}
Considering this case, leader is "cstate_pkg/c2-residency", evsel is
"msr/tsc" and cpu is 1. Because "cstate_pkg/c2-residency" is a system-wide
event and it's processed on CPU0, so FD(leader, 1, thread) must return an
invalid fd, then BUG_ON() may be triggered.
This patch gets group fd from CPU0 for system wide event if
FD(leader, cpu, thread) returns invalid fd.
With this patch,
# perf stat -M "C2_Pkg_Residency" -a -- sleep 1
Performance counter stats for 'system wide':
1000850802 cstate_pkg/c2-residency/ # 0.5 C2_Pkg_Residency
201446161592 msr/tsc/
1.010637051 seconds time elapsed
Fixes: 6a4bb04caacc ("perf tools: Enable grouping logic for parsed events")
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
tools/perf/util/evsel.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 6a571d322bb2..cd6470f63d6f 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1461,6 +1461,9 @@ static int get_group_fd(struct evsel *evsel, int cpu, int thread)
BUG_ON(!leader->core.fd);
fd = FD(leader, cpu, thread);
+ if (fd == -1 && leader->core.system_wide)
+ fd = FD(leader, 0, thread);
+
BUG_ON(fd == -1);
return fd;
--
2.17.1
next reply other threads:[~2020-04-30 1:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 1:34 Jin Yao [this message]
2020-05-01 10:23 ` [PATCH] perf evsel: Get group fd from CPU0 for system wide event Jiri Olsa
2020-05-02 2:33 ` Jin, Yao
2020-05-05 0:03 ` Jiri Olsa
2020-05-09 7:37 ` Jin, Yao
2020-05-15 6:04 ` Jin, Yao
2020-05-15 8:33 ` Jiri Olsa
2020-05-18 3:28 ` Jin, Yao
2020-05-20 5:36 ` Jin, Yao
2020-05-20 7:50 ` Jiri Olsa
2020-05-21 4:38 ` Jin, Yao
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