From: kan.liang@intel.com
To: acme@kernel.org, peterz@infradead.org, mingo@redhat.com,
linux-kernel@vger.kernel.org
Cc: jolsa@kernel.org, namhyung@kernel.org, adrian.hunter@intel.com,
lukasz.odzioba@intel.com, ak@linux.intel.com,
Kan Liang <kan.liang@intel.com>
Subject: [PATCH RFC 02/10] perf tools: using scandir to replace readdir
Date: Thu, 7 Sep 2017 10:55:46 -0700 [thread overview]
Message-ID: <1504806954-150842-3-git-send-email-kan.liang@intel.com> (raw)
In-Reply-To: <1504806954-150842-1-git-send-email-kan.liang@intel.com>
From: Kan Liang <kan.liang@intel.com>
For perf_event__synthesize_threads, perf goes through all proc files
serially by readdir.
scandir did a snapshoot of proc, which is multithreading friendly.
It's possible that some threads which are added during event synthesize.
But the number of lost threads should be small.
They should not impact the final analysis.
Signed-off-by: Kan Liang <kan.liang@intel.com>
---
tools/perf/util/event.c | 45 +++++++++++++++++++++++++--------------------
1 file changed, 25 insertions(+), 20 deletions(-)
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 1c905ba..17c21ea 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -683,12 +683,14 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
bool mmap_data,
unsigned int proc_map_timeout)
{
- DIR *proc;
- char proc_path[PATH_MAX];
- struct dirent *dirent;
union perf_event *comm_event, *mmap_event, *fork_event;
union perf_event *namespaces_event;
+ char proc_path[PATH_MAX];
+ struct dirent **dirent;
int err = -1;
+ char *end;
+ pid_t pid;
+ int n, i;
if (machine__is_default_guest(machine))
return 0;
@@ -712,29 +714,32 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
goto out_free_fork;
snprintf(proc_path, sizeof(proc_path), "%s/proc", machine->root_dir);
- proc = opendir(proc_path);
+ n = scandir(proc_path, &dirent, 0, alphasort);
- if (proc == NULL)
+ if (n < 0)
goto out_free_namespaces;
- while ((dirent = readdir(proc)) != NULL) {
- char *end;
- pid_t pid = strtol(dirent->d_name, &end, 10);
-
- if (*end) /* only interested in proper numerical dirents */
+ for (i = 0; i < n; i++) {
+ if (!isdigit(dirent[i]->d_name[0]))
continue;
- /*
- * We may race with exiting thread, so don't stop just because
- * one thread couldn't be synthesized.
- */
- __event__synthesize_thread(comm_event, mmap_event, fork_event,
- namespaces_event, pid, 1, process,
- tool, machine, mmap_data,
- proc_map_timeout);
- }
+ pid = (pid_t)strtol(dirent[i]->d_name, &end, 10);
+ /* only interested in proper numerical dirents */
+ if (!*end) {
+ /*
+ * We may race with exiting thread, so don't stop just because
+ * one thread couldn't be synthesized.
+ */
+ __event__synthesize_thread(comm_event, mmap_event, fork_event,
+ namespaces_event, pid, 1, process,
+ tool, machine, mmap_data,
+ proc_map_timeout);
+ }
+ free(dirent[i]);
+ }
+ free(dirent);
err = 0;
- closedir(proc);
+
out_free_namespaces:
free(namespaces_event);
out_free_fork:
--
2.5.5
next prev parent reply other threads:[~2017-09-07 17:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-07 17:55 [PATCH RFC 00/10] perf top optimization kan.liang
2017-09-07 17:55 ` [PATCH RFC 01/10] perf tools: hashtable for machine threads kan.liang
2017-09-08 14:18 ` Arnaldo Carvalho de Melo
2017-09-07 17:55 ` kan.liang [this message]
2017-09-08 14:11 ` [PATCH RFC 02/10] perf tools: using scandir to replace readdir Arnaldo Carvalho de Melo
2017-09-22 16:35 ` [tip:perf/core] perf tools: Use scandir() to replace readdir() tip-bot for Kan Liang
2017-09-07 17:55 ` [PATCH RFC 03/10] petf tools: using comm_str to replace comm in hist_entry kan.liang
2017-09-07 17:55 ` [PATCH RFC 04/10] petf tools: introduce a new function to set namespaces id kan.liang
2017-09-07 17:55 ` [PATCH RFC 05/10] perf tools: lock to protect thread list kan.liang
2017-09-07 17:55 ` [PATCH RFC 06/10] perf tools: lock to protect comm_str rb tree kan.liang
2017-09-08 14:27 ` Arnaldo Carvalho de Melo
2017-09-07 17:55 ` [PATCH RFC 07/10] perf tools: change machine comm_exec type to atomic kan.liang
2017-09-07 17:55 ` [PATCH RFC 08/10] perf top: implement multithreading for perf_event__synthesize_threads kan.liang
2017-09-07 17:55 ` [PATCH RFC 09/10] perf top: add option to set the number of thread for event synthesize kan.liang
2017-09-07 17:55 ` [PATCH RFC 10/10] perf top: switch back to overwrite mode kan.liang
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