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Message-Id: <a5fee5068f9630f14f1f5c259434badf43d451c4.1626177381.git.rickyman7@gmail.com>
Date: Tue, 13 Jul 2021 14:11:15 +0200
From: Riccardo Mancini <rickyman7@...il.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>,
Namhyung Kim <namhyung@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org,
Riccardo Mancini <rickyman7@...il.com>
Subject: [RFC PATCH 04/10] perf workqueue: add threadpool execute and wait functions
This patch adds:
- execute_in_threadpool: assigns a task to the threads to execute
asynchronously.
- wait_threadpool: waits for the task to complete on all threads.
Furthermore, testing for these new functions is added.
This patch completes the threadpool.
Signed-off-by: Riccardo Mancini <rickyman7@...il.com>
---
tools/perf/tests/workqueue.c | 86 ++++++++++++++++++++-
tools/perf/util/workqueue/threadpool.c | 103 +++++++++++++++++++++++++
tools/perf/util/workqueue/threadpool.h | 5 ++
3 files changed, 193 insertions(+), 1 deletion(-)
diff --git a/tools/perf/tests/workqueue.c b/tools/perf/tests/workqueue.c
index be377e9897bab4e9..3c64db8203556847 100644
--- a/tools/perf/tests/workqueue.c
+++ b/tools/perf/tests/workqueue.c
@@ -1,13 +1,59 @@
// SPDX-License-Identifier: GPL-2.0
+#include <stdlib.h>
#include <linux/kernel.h>
+#include <linux/zalloc.h>
#include "tests.h"
#include "util/debug.h"
#include "util/workqueue/threadpool.h"
+#define DUMMY_FACTOR 100000
+#define N_DUMMY_WORK_SIZES 7
+
struct threadpool_test_args_t {
int pool_size;
};
+struct test_task {
+ struct task_struct task;
+ int n_threads;
+ int *array;
+};
+
+/**
+ * dummy_work - calculates DUMMY_FACTOR * (idx % N_DUMMY_WORK_SIZES) inefficiently
+ *
+ * This function uses modulus to create work items of different sizes.
+ */
+static void dummy_work(int idx)
+{
+ int prod = 0;
+ int k = idx % N_DUMMY_WORK_SIZES;
+ int i, j;
+
+ for (i = 0; i < DUMMY_FACTOR; i++)
+ for (j = 0; j < k; j++)
+ prod ++;
+
+ pr_debug3("dummy: %d * %d = %d\n", DUMMY_FACTOR, k, prod);
+}
+
+static void test_task_fn1(int tidx, struct task_struct *task)
+{
+ struct test_task *mtask = container_of(task, struct test_task, task);
+
+ dummy_work(tidx);
+ mtask->array[tidx] = tidx+1;
+}
+
+static void test_task_fn2(int tidx, struct task_struct *task)
+{
+ struct test_task *mtask = container_of(task, struct test_task, task);
+
+ dummy_work(tidx);
+ mtask->array[tidx] = tidx*2;
+}
+
+
static int __threadpool__prepare(struct threadpool_struct **pool, int pool_size)
{
int ret;
@@ -38,21 +84,59 @@ static int __threadpool__teardown(struct threadpool_struct *pool)
return 0;
}
+static int __threadpool__exec_wait(struct threadpool_struct *pool,
+ struct task_struct *task)
+{
+ int ret;
+
+ ret = execute_in_threadpool(pool, task);
+ TEST_ASSERT_VAL("threadpool execute failure", ret == 0);
+ TEST_ASSERT_VAL("threadpool is not executing", threadpool_is_busy(pool));
+
+ ret = wait_threadpool(pool);
+ TEST_ASSERT_VAL("threadpool wait failure", ret == 0);
+ TEST_ASSERT_VAL("waited threadpool is not ready", threadpool_is_ready(pool));
+
+ return 0;
+}
static int __test__threadpool(void *_args)
{
struct threadpool_test_args_t *args = _args;
struct threadpool_struct *pool;
- int ret;
+ int ret, i;
+ struct test_task task;
+
+ task.task.fn = test_task_fn1;
+ task.n_threads = args->pool_size;
+ task.array = calloc(args->pool_size, sizeof(*task.array));
ret = __threadpool__prepare(&pool, args->pool_size);
if (ret)
return ret;
+ ret = __threadpool__exec_wait(pool, &task.task);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < args->pool_size; i++)
+ TEST_ASSERT_VAL("failed array check (1)", task.array[i] == i+1);
+
+ task.task.fn = test_task_fn2;
+
+ ret = __threadpool__exec_wait(pool, &task.task);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < args->pool_size; i++)
+ TEST_ASSERT_VAL("failed array check (2)", task.array[i] == 2*i);
+
ret = __threadpool__teardown(pool);
if (ret)
return ret;
+ free(task.array);
+
return 0;
}
diff --git a/tools/perf/util/workqueue/threadpool.c b/tools/perf/util/workqueue/threadpool.c
index f4635ff782b9388e..720c7b2a562d6816 100644
--- a/tools/perf/util/workqueue/threadpool.c
+++ b/tools/perf/util/workqueue/threadpool.c
@@ -21,6 +21,7 @@ static inline pid_t gettid(void)
enum threadpool_status {
THREADPOOL_STATUS__STOPPED, /* no threads */
THREADPOOL_STATUS__READY, /* threads are ready but idle */
+ THREADPOOL_STATUS__BUSY, /* threads are busy */
THREADPOOL_STATUS__ERROR, /* errors */
THREADPOOL_STATUS__MAX
};
@@ -164,6 +165,28 @@ static int terminate_thread(struct thread_struct *thread)
return res;
}
+/**
+ * wake_thread - send wake msg to @thread
+ *
+ * This function does not wait for the thread to actually wake
+ * NB: call only from main thread!
+ */
+static int wake_thread(struct thread_struct *thread)
+{
+ int res;
+ enum thread_msg msg = THREAD_MSG__WAKE;
+
+ res = write(thread->pipes.to[1], &msg, sizeof(msg));
+ if (res < 0) {
+ pr_err("threadpool: error sending wake msg: %s\n", strerror(errno));
+ return -1;
+ }
+
+ pr_debug2("threadpool: sent wake msg %s to tid=%d\n",
+ thread_msg_tags[msg], thread->tid);
+ return 0;
+}
+
/**
* threadpool_thread - function running on thread
*
@@ -207,6 +230,15 @@ static void *threadpool_thread(void *args)
if (msg == THREAD_MSG__STOP)
break;
+
+ if (!thread->pool->current_task) {
+ pr_err("threadpool[%d]: received wake without task\n",
+ thread->tid);
+ break;
+ }
+
+ pr_debug("threadpool[%d]: executing task\n", thread->tid);
+ thread->pool->current_task->fn(thread->idx, thread->pool->current_task);
}
pr_debug2("threadpool[%d]: exit\n", thread->tid);
@@ -383,11 +415,16 @@ int start_threadpool(struct threadpool_struct *pool)
* stop_threadpool - stop all threads in the pool.
*
* This function blocks waiting for ack from all threads.
+ * If the pool was busy, it will first wait for the task to finish.
*/
int stop_threadpool(struct threadpool_struct *pool)
{
int t, ret, err = 0;
+ err = wait_threadpool(pool);
+ if (err)
+ return err;
+
if (pool->status != THREADPOOL_STATUS__READY) {
pr_err("threadpool: stopping not ready pool\n");
return -1;
@@ -411,3 +448,69 @@ bool threadpool_is_ready(struct threadpool_struct *pool)
{
return pool->status == THREADPOOL_STATUS__READY;
}
+
+/**
+ * execute_in_threadpool - execute @task on all threads of the @pool
+ *
+ * The task will run asynchronously wrt the main thread.
+ * The task can be waited with wait_threadpool.
+ *
+ * NB: make sure the pool is ready before calling this, since no queueing is
+ * performed. If you need queueing, have a look at the workqueue.
+ */
+int execute_in_threadpool(struct threadpool_struct *pool, struct task_struct *task)
+{
+ int t, err;
+
+ WARN_ON(pool->status != THREADPOOL_STATUS__READY);
+
+ pool->current_task = task;
+
+ for (t = 0; t < pool->nr_threads; t++) {
+ err = wake_thread(&pool->threads[t]);
+
+ if (err) {
+ pool->status = THREADPOOL_STATUS__ERROR;
+ return err;
+ }
+ }
+
+ pool->status = THREADPOOL_STATUS__BUSY;
+ return 0;
+}
+
+/**
+ * wait_threadpool - wait until all threads in @pool are done
+ *
+ * This function will wait for all threads to finish execution and send their
+ * ack message.
+ *
+ * NB: call only from main thread!
+ */
+int wait_threadpool(struct threadpool_struct *pool)
+{
+ int t, err = 0, ret;
+
+ if (pool->status != THREADPOOL_STATUS__BUSY)
+ return 0;
+
+ for (t = 0; t < pool->nr_threads; t++) {
+ ret = wait_thread(&pool->threads[t]);
+ if (ret) {
+ pool->status = THREADPOOL_STATUS__ERROR;
+ err = -1;
+ }
+ }
+
+ pool->status = err ? THREADPOOL_STATUS__ERROR : THREADPOOL_STATUS__READY;
+ pool->current_task = NULL;
+ return err;
+}
+
+/**
+ * threadpool_is_busy - check if the pool is busy
+ */
+int threadpool_is_busy(struct threadpool_struct *pool)
+{
+ return pool->status == THREADPOOL_STATUS__BUSY;
+}
diff --git a/tools/perf/util/workqueue/threadpool.h b/tools/perf/util/workqueue/threadpool.h
index b62cad2b2c5dd331..dd9c2103ebe8d23b 100644
--- a/tools/perf/util/workqueue/threadpool.h
+++ b/tools/perf/util/workqueue/threadpool.h
@@ -17,8 +17,13 @@ extern void destroy_threadpool(struct threadpool_struct *pool);
extern int start_threadpool(struct threadpool_struct *pool);
extern int stop_threadpool(struct threadpool_struct *pool);
+extern int execute_in_threadpool(struct threadpool_struct *pool,
+ struct task_struct *task);
+extern int wait_threadpool(struct threadpool_struct *pool);
+
extern int threadpool_size(struct threadpool_struct *pool);
extern bool threadpool_is_ready(struct threadpool_struct *pool);
+extern int threadpool_is_busy(struct threadpool_struct *pool);
#endif /* __WORKQUEUE_THREADPOOL_H */
--
2.31.1
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