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Message-ID: <20241031223948.4179222-3-ctshao@google.com>
Date: Thu, 31 Oct 2024 22:39:45 +0000
From: Chun-Tse Shao <ctshao@...gle.com>
To: linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, Liang@...gle.com,
Kan <kan.liang@...ux.intel.com>, Ze Gao <zegao2021@...il.com>,
Chun-Tse Shao <ctshao@...gle.com>, Yang Jihong <yangjihong1@...wei.com>,
Weilin Wang <weilin.wang@...el.com>, linux-perf-users@...r.kernel.org
Subject: [PATCH 3/3] perf evsel: Find process with busy PMUs for EBUSY
It parses fdinfo with PMU type, comparing with the event which failed to
open, and report the processes causing EBUSY error.
```
Testing cycles and intel_pt//
$ ./perf stat -e cycles &
[1] 55569
$ ./perf stat -e intel_pt// &
[2] 55683
$ ./perf stat -e intel_pt//
Error:
The PMU intel_pt counters are busy and in use by another process.
Possible processes:
55683 ./perf stat -e intel_pt//
```
Only perf with intel_pt was reported.
Signed-off-by: Chun-Tse Shao <ctshao@...gle.com>
---
tools/perf/util/evsel.c | 79 +++++++++++++++++++++++++++++------------
1 file changed, 57 insertions(+), 22 deletions(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 9a5b6a6f8d2e5..d2f7c19e023ec 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -3286,7 +3286,8 @@ static bool find_process(const char *name)
return ret ? false : true;
}
-static int dump_perf_event_processes(char *msg, size_t size)
+static int dump_perf_event_processes(const struct perf_event_attr *failed_attr,
+ char *msg, size_t size)
{
DIR *proc_dir;
struct dirent *proc_entry;
@@ -3327,29 +3328,61 @@ static int dump_perf_event_processes(char *msg, size_t size)
continue;
/* Take care as readlink doesn't null terminate the string. */
if (!strncmp(path, "anon_inode:[perf_event]", link_size)) {
- int cmdline_fd;
- ssize_t cmdline_size;
-
- scnprintf(path, sizeof(path), "%s/cmdline", proc_entry->d_name);
- cmdline_fd = openat(dirfd(proc_dir), path, O_RDONLY);
- if (cmdline_fd == -1)
- continue;
- cmdline_size = read(cmdline_fd, path, sizeof(path) - 1);
- close(cmdline_fd);
- if (cmdline_size < 0)
+ int fdinfo_fd;
+ ssize_t fdinfo_size;
+ char *line;
+ u32 perf_event_type = PERF_TYPE_MAX;
+
+ /* Let's check the PMU type reserved by this process */
+ scnprintf(path, sizeof(path), "%s/fdinfo/%s",
+ proc_entry->d_name, fd_entry->d_name);
+ fdinfo_fd = openat(dirfd(proc_dir), path, O_RDONLY);
+ fdinfo_size = read(fdinfo_fd, path, sizeof(path) - 1);
+ if (fdinfo_size < 0)
continue;
- path[cmdline_size] = '\0';
- for (ssize_t i = 0; i < cmdline_size; i++) {
- if (path[i] == '\0')
- path[i] = ' ';
+ path[fdinfo_size] = '\0';
+
+ line = strtok(path, "\n");
+ while (line != NULL) {
+ if (sscanf(line,
+ "perf_event-attr.type:\t%u",
+ &perf_event_type) == 1)
+ break;
+ line = strtok(NULL, "\n");
}
- if (printed == 0)
- printed += scnprintf(msg, size, "Possible processes:\n");
-
- printed += scnprintf(msg + printed, size - printed,
- "%s %s\n", proc_entry->d_name, path);
- break;
+ /* Report the process which reserves the conflicted PMU. */
+ /* If fdinfo does not contain PMU type, report it too. */
+ if (perf_event_type == failed_attr->type ||
+ perf_event_type == PERF_TYPE_MAX) {
+ int cmdline_fd;
+ ssize_t cmdline_size;
+
+ scnprintf(path, sizeof(path),
+ "%s/cmdline",
+ proc_entry->d_name);
+ cmdline_fd = openat(dirfd(proc_dir), path, O_RDONLY);
+ if (cmdline_fd == -1)
+ continue;
+ cmdline_size = read(cmdline_fd, path, sizeof(path) - 1);
+ close(cmdline_fd);
+ if (cmdline_size < 0)
+ continue;
+ path[cmdline_size] = '\0';
+ for (ssize_t i = 0; i < cmdline_size; i++) {
+ if (path[i] == '\0')
+ path[i] = ' ';
+ }
+
+ if (printed == 0)
+ printed += scnprintf(
+ msg, size,
+ "Possible processes:\n");
+
+ printed += scnprintf(msg + printed, size - printed,
+ "%s %s\n", proc_entry->d_name, path);
+ break;
+ }
}
}
closedir(fd_dir);
@@ -3458,7 +3491,9 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
msg, size,
"The PMU %s counters are busy and in use by another process.\n",
evsel->pmu ? evsel->pmu->name : "");
- return printed + dump_perf_event_processes(msg + printed, size - printed);
+ return printed + dump_perf_event_processes(&evsel->core.attr,
+ msg + printed,
+ size - printed);
break;
case EINVAL:
if (evsel->core.attr.sample_type & PERF_SAMPLE_CODE_PAGE_SIZE && perf_missing_features.code_page_size)
--
2.47.0.163.g1226f6d8fa-goog
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