From: Tejun Heo <tj@kernel.org>
To: torvalds@linux-foundation.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
kernel-team@fb.com, csmall@enc.com.au, Tejun Heo <tj@kernel.org>
Subject: [PATCH 6/6] workqueue: Show the latest workqueue name in /proc/PID/{comm,stat,status}
Date: Wed, 16 May 2018 21:34:48 -0700 [thread overview]
Message-ID: <20180517043448.3152269-7-tj@kernel.org> (raw)
In-Reply-To: <20180517043448.3152269-1-tj@kernel.org>
There can be a lot of workqueue workers and they all show up with the
cryptic kworker/* names making it difficult to understand which is
doing what and how they came to be.
# ps -ef | grep kworker
root 4 2 0 Feb25 ? 00:00:00 [kworker/0:0H]
root 6 2 0 Feb25 ? 00:00:00 [kworker/u112:0]
root 19 2 0 Feb25 ? 00:00:00 [kworker/1:0H]
root 25 2 0 Feb25 ? 00:00:00 [kworker/2:0H]
root 31 2 0 Feb25 ? 00:00:00 [kworker/3:0H]
...
This patch makes workqueue workers report the latest workqueue it was
executing for through /proc/PID/{comm,stat,status}. The extra
information is appended to the kthread name with intervening '+' if
currently executing, otherwise '-'.
# cat /proc/25/comm
kworker/2:0-events_power_efficient
# cat /proc/25/stat
25 (kworker/2:0-events_power_efficient) I 2 0 0 0 -1 69238880 0 0...
# grep Name /proc/25/status
Name: kworker/2:0-events_power_efficient
Unfortunately, ps(1) truncates comm to 15 characters,
# ps 25
PID TTY STAT TIME COMMAND
25 ? I 0:00 [kworker/2:0-eve]
making it a lot less useful; however, this should be an easy fix from
ps(1) side.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Craig Small <csmall@enc.com.au>
---
fs/proc/array.c | 7 +++++--
include/linux/workqueue.h | 1 +
kernel/workqueue.c | 39 +++++++++++++++++++++++++++++++++++++++
3 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c
index f29221e..bb1d361 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -99,10 +99,13 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
{
char *buf;
size_t size;
- char tcomm[sizeof(p->comm)];
+ char tcomm[64];
int ret;
- get_task_comm(tcomm, p);
+ if (p->flags & PF_WQ_WORKER)
+ wq_worker_comm(tcomm, sizeof(tcomm), p);
+ else
+ __get_task_comm(tcomm, sizeof(tcomm), p);
size = seq_get_buf(m, &buf);
if (escape) {
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 39a0e21..60d673e 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -494,6 +494,7 @@ extern unsigned int work_busy(struct work_struct *work);
extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
extern void print_worker_info(const char *log_lvl, struct task_struct *task);
extern void show_workqueue_state(void);
+extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task);
/**
* queue_work - queue work on a workqueue
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 3fbe007..b4a39a1 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4577,6 +4577,45 @@ void show_workqueue_state(void)
rcu_read_unlock_sched();
}
+/* used to show worker information through /proc/PID/{comm,stat,status} */
+void wq_worker_comm(char *buf, size_t size, struct task_struct *task)
+{
+ struct worker *worker;
+ struct worker_pool *pool;
+ int off;
+
+ /* always show the actual comm */
+ off = strscpy(buf, task->comm, size);
+ if (off < 0)
+ return;
+
+ /* stabilize worker pool association */
+ mutex_lock(&wq_pool_attach_mutex);
+
+ worker = kthread_data(task);
+ pool = worker->pool;
+
+ if (pool) {
+ spin_lock_irq(&pool->lock);
+ /*
+ * ->desc tracks information (wq name or set_worker_desc())
+ * for the latest execution. If current, prepend '+',
+ * otherwise '-'.
+ */
+ if (worker->desc[0] != '\0') {
+ if (worker->current_work)
+ scnprintf(buf + off, size - off, "+%s",
+ worker->desc);
+ else
+ scnprintf(buf + off, size - off, "-%s",
+ worker->desc);
+ }
+ spin_unlock_irq(&pool->lock);
+ }
+
+ mutex_unlock(&wq_pool_attach_mutex);
+}
+
/*
* CPU hotplug.
*
--
2.9.5
prev parent reply other threads:[~2018-05-17 4:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-17 4:34 [PATCHSET] workqueue: Show the latest workqueue name in /proc/PID/{comm,stat,status} Tejun Heo
2018-05-17 4:34 ` [PATCH 1/6] proc: Don't allow empty /proc/PID/cmdline for user tasks Tejun Heo
2018-05-17 4:34 ` [PATCH 2/6] workqueue: Replace pool->attach_mutex with global wq_pool_attach_mutex Tejun Heo
2018-05-17 4:34 ` [PATCH 3/6] workqueue: Make worker_attach/detach_pool() update worker->pool Tejun Heo
2018-05-19 6:44 ` Lai Jiangshan
2018-05-17 4:34 ` [PATCH 4/6] workqueue: Set worker->desc to workqueue name by default Tejun Heo
2018-05-17 4:34 ` [PATCH 5/6] proc: Consolidate task->comm formatting into proc_task_name() Tejun Heo
2018-05-17 4:34 ` Tejun Heo [this message]
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