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Date: Wed, 14 Jul 2021 12:15:43 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Riccardo Mancini <rickyman7@...il.com>
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,
Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>
Subject: Re: [RFC PATCH 03/10] perf workqueue: add threadpool start and stop
functions
Em Tue, Jul 13, 2021 at 02:11:14PM +0200, Riccardo Mancini escreveu:
> This patch adds the start and stop functions, alongside the thread
> function.
> Each thread will run until a stop signal is received.
> Furthermore, start and stop are added to the test.
>
> Thread management is based on the prototype from Alexey:
> https://lore.kernel.org/lkml/cover.1625227739.git.alexey.v.bayduraev@linux.intel.com/
>
> Suggested-by: Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>
> Signed-off-by: Riccardo Mancini <rickyman7@...il.com>
> ---
> tools/perf/tests/workqueue.c | 13 ++
> tools/perf/util/workqueue/threadpool.c | 238 +++++++++++++++++++++++++
> tools/perf/util/workqueue/threadpool.h | 5 +
> 3 files changed, 256 insertions(+)
>
> diff --git a/tools/perf/tests/workqueue.c b/tools/perf/tests/workqueue.c
> index 1bd4d78c13eb3b14..be377e9897bab4e9 100644
> --- a/tools/perf/tests/workqueue.c
> +++ b/tools/perf/tests/workqueue.c
> @@ -10,16 +10,29 @@ struct threadpool_test_args_t {
>
> static int __threadpool__prepare(struct threadpool_struct **pool, int pool_size)
> {
> + int ret;
> +
> *pool = create_threadpool(pool_size);
> TEST_ASSERT_VAL("threadpool creation failure", *pool != NULL);
> TEST_ASSERT_VAL("threadpool size is wrong",
> threadpool_size(*pool) == pool_size);
>
> + ret = start_threadpool(*pool);
> + TEST_ASSERT_VAL("threadpool start failure", ret == 0);
> + TEST_ASSERT_VAL("threadpool is not ready", threadpool_is_ready(*pool));
> +
> return 0;
> }
>
> static int __threadpool__teardown(struct threadpool_struct *pool)
> {
> + int ret;
> +
> + ret = stop_threadpool(pool);
int ret = stop_threadpool(pool);
> + TEST_ASSERT_VAL("threadpool start failure", ret == 0);
> + TEST_ASSERT_VAL("stopped threadpool is ready",
> + !threadpool_is_ready(pool));
> +
> destroy_threadpool(pool);
>
> return 0;
> diff --git a/tools/perf/util/workqueue/threadpool.c b/tools/perf/util/workqueue/threadpool.c
> index 70c67569f956a3e2..f4635ff782b9388e 100644
> --- a/tools/perf/util/workqueue/threadpool.c
> +++ b/tools/perf/util/workqueue/threadpool.c
> @@ -4,12 +4,23 @@
> #include <unistd.h>
> #include <errno.h>
> #include <string.h>
> +#include <pthread.h>
> +#include <signal.h>
> +#include <syscall.h>
> #include "debug.h"
> #include "asm/bug.h"
> #include "threadpool.h"
>
> +#ifndef HAVE_GETTID
> +static inline pid_t gettid(void)
> +{
> + return (pid_t)syscall(__NR_gettid);
> +}
> +#endif
Isn't this defined elsewhere? Yeah, when we decide to move it to
tools/lib/workqueue/ we'll need it, but for now, reduce patch size.
> enum threadpool_status {
> THREADPOOL_STATUS__STOPPED, /* no threads */
> + THREADPOOL_STATUS__READY, /* threads are ready but idle */
> THREADPOOL_STATUS__ERROR, /* errors */
> THREADPOOL_STATUS__MAX
> };
> @@ -31,6 +42,21 @@ struct thread_struct {
> } pipes;
> };
>
> +enum thread_msg {
> + THREAD_MSG__UNDEFINED = 0,
> + THREAD_MSG__ACK, /* from th: create and exit ack */
> + THREAD_MSG__WAKE, /* to th: wake up */
> + THREAD_MSG__STOP, /* to th: exit */
> + THREAD_MSG__MAX
> +};
> +
> +static const char * const thread_msg_tags[] = {
> + "undefined",
> + "ack",
> + "wake",
> + "stop"
> +};
> +
> /**
> * init_pipes - initialize all pipes of @thread
> */
> @@ -89,6 +115,113 @@ static void close_pipes(struct thread_struct *thread)
> }
> }
>
> +/**
> + * wait_thread - receive ack from thread
> + *
> + * NB: call only from main thread!
> + */
> +static int wait_thread(struct thread_struct *thread)
> +{
> + int res;
> + enum thread_msg msg = THREAD_MSG__UNDEFINED;
> +
> + res = read(thread->pipes.from[0], &msg, sizeof(msg));
int res = read(thread->pipes.from[0], &msg, sizeof(msg));
> + if (res < 0) {
> + pr_err("threadpool: failed to recv msg from tid=%d: %s\n",
> + thread->tid, strerror(errno));
> + return -1;
> + }
> + if (msg != THREAD_MSG__ACK) {
> + pr_err("threadpool: received unexpected msg from tid=%d: %s\n",
> + thread->tid, thread_msg_tags[msg]);
> + return -1;
> + }
> +
> + pr_debug2("threadpool: received ack from tid=%d\n", thread->tid);
> +
> + return 0;
> +}
> +
> +/**
> + * terminate_thread - send stop signal to thread and wait for ack
> + *
> + * NB: call only from main thread!
> + */
> +static int terminate_thread(struct thread_struct *thread)
> +{
> + int res;
> + enum thread_msg msg = THREAD_MSG__STOP;
> +
> + res = write(thread->pipes.to[1], &msg, sizeof(msg));
> + if (res < 0) {
> + pr_err("threadpool: error sending stop msg to tid=%d: %s\n",
> + thread->tid, strerror(errno));
> + return res;
> + }
> +
> + res = wait_thread(thread);
> +
> + return res;
> +}
> +
> +/**
> + * threadpool_thread - function running on thread
> + *
> + * This function waits for a signal from main thread to start executing
> + * a task.
> + * On completion, it will go back to sleep, waiting for another signal.
> + * Signals are delivered through pipes.
> + */
> +static void *threadpool_thread(void *args)
threadpool_function()
ETOMANY 'thread' in a name.
> +{
> + struct thread_struct *thread = (struct thread_struct *) args;
> + enum thread_msg msg;
> + int err;
> +
> + thread->tid = gettid();
> +
> + pr_debug2("threadpool[%d]: started\n", thread->tid);
> +
> + for (;;) {
> + msg = THREAD_MSG__ACK;
> + err = write(thread->pipes.from[1], &msg, sizeof(msg));
> + if (err == -1) {
> + pr_err("threadpool[%d]: failed to send ack: %s\n",
> + thread->tid, strerror(errno));
> + break;
> + }
> +
> + msg = THREAD_MSG__UNDEFINED;
> + err = read(thread->pipes.to[0], &msg, sizeof(msg));
> + if (err < 0) {
> + pr_err("threadpool[%d]: error receiving msg: %s\n",
> + thread->tid, strerror(errno));
> + break;
> + }
> +
> + if (msg != THREAD_MSG__WAKE && msg != THREAD_MSG__STOP) {
> + pr_err("threadpool[%d]: received unexpected msg: %s\n",
> + thread->tid, thread_msg_tags[msg]);
> + break;
> + }
> +
> + if (msg == THREAD_MSG__STOP)
> + break;
> + }
> +
> + pr_debug2("threadpool[%d]: exit\n", thread->tid);
> +
> + msg = THREAD_MSG__ACK;
> + err = write(thread->pipes.from[1], &msg, sizeof(msg));
> + if (err == -1) {
> + pr_err("threadpool[%d]: failed to send ack: %s\n",
> + thread->tid, strerror(errno));
> + return NULL;
> + }
> +
> + return NULL;
> +}
> +
> /**
> * create_threadpool - create a fixed threadpool with @n_threads threads
> */
> @@ -173,3 +306,108 @@ int threadpool_size(struct threadpool_struct *pool)
> {
> return pool->nr_threads;
> }
> +
> +/**
> + * __start_threadpool - start all threads in the pool.
> + *
> + * This function does not change @pool->status.
> + */
> +static int __start_threadpool(struct threadpool_struct *pool)
> +{
> + int t, tt, ret = 0, nr_threads = pool->nr_threads;
> + sigset_t full, mask;
> + pthread_t handle;
> + pthread_attr_t attrs;
> +
> + sigfillset(&full);
> + if (sigprocmask(SIG_SETMASK, &full, &mask)) {
> + pr_err("Failed to block signals on threads start: %s\n",
> + strerror(errno));
> + return -1;
> + }
> +
> + pthread_attr_init(&attrs);
> + pthread_attr_setdetachstate(&attrs, PTHREAD_CREATE_DETACHED);
> +
> + for (t = 0; t < nr_threads; t++) {
> + struct thread_struct *thread = &pool->threads[t];
> +
> + if (pthread_create(&handle, &attrs, threadpool_thread, thread)) {
> + for (tt = 1; tt < t; tt++)
> + terminate_thread(thread);
> + pr_err("Failed to start threads: %s\n", strerror(errno));
> + ret = -1;
> + goto out_free_attr;
> + }
> +
> + if (wait_thread(thread)) {
> + for (tt = 1; tt <= t; tt++)
> + terminate_thread(thread);
> + ret = -1;
> + goto out_free_attr;
> + }
> + }
> +
> +out_free_attr:
> + pthread_attr_destroy(&attrs);
> +
> + if (sigprocmask(SIG_SETMASK, &mask, NULL)) {
> + pr_err("Failed to unblock signals on threads start: %s\n",
> + strerror(errno));
> + ret = -1;
> + }
> +
> + return ret;
> +}
> +
> +/**
> + * start_threadpool - start all threads in the pool.
> + *
> + * The function blocks until all threads are up and running.
> + */
> +int start_threadpool(struct threadpool_struct *pool)
int threadpool__start(struct threadpool *pool)
> +{
> + int err;
> +
> + if (pool->status != THREADPOOL_STATUS__STOPPED) {
> + pr_err("threadpool: starting not stopped pool\n");
> + return -1;
> + }
> +
> + err = __start_threadpool(pool);
> + pool->status = err ? THREADPOOL_STATUS__ERROR : THREADPOOL_STATUS__READY;
> + return err;
> +}
> +
> +/**
> + * stop_threadpool - stop all threads in the pool.
> + *
> + * This function blocks waiting for ack from all threads.
> + */
> +int stop_threadpool(struct threadpool_struct *pool)
int threadpool__stop(struct threadpool *pool)
> +{
> + int t, ret, err = 0;
> +
> + if (pool->status != THREADPOOL_STATUS__READY) {
> + pr_err("threadpool: stopping not ready pool\n");
> + return -1;
> + }
> +
> + for (t = 0; t < pool->nr_threads; t++) {
> + ret = terminate_thread(&pool->threads[t]);
> + if (ret && !err)
> + err = -1;
> + }
> +
> + pool->status = err ? THREADPOOL_STATUS__ERROR : THREADPOOL_STATUS__STOPPED;
> +
> + return err;
> +}
> +
> +/**
> + * threadpool_is_ready - check if the threads are running
> + */
> +bool threadpool_is_ready(struct threadpool_struct *pool)
bool threadpool__is_ready(struct threadpool *pool)
> +{
> + return pool->status == THREADPOOL_STATUS__READY;
> +}
> diff --git a/tools/perf/util/workqueue/threadpool.h b/tools/perf/util/workqueue/threadpool.h
> index 2b9388c768a0b588..b62cad2b2c5dd331 100644
> --- a/tools/perf/util/workqueue/threadpool.h
> +++ b/tools/perf/util/workqueue/threadpool.h
> @@ -14,6 +14,11 @@ struct task_struct {
> extern struct threadpool_struct *create_threadpool(int n_threads);
> 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 threadpool_size(struct threadpool_struct *pool);
>
> +extern bool threadpool_is_ready(struct threadpool_struct *pool);
> +
> #endif /* __WORKQUEUE_THREADPOOL_H */
> --
> 2.31.1
>
--
- Arnaldo
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