selftests: ublk: make ublk_thread thread-local variable

Refactor ublk_thread to be a thread-local variable instead of storing
it in ublk_dev:

- Remove pthread_t thread field from struct ublk_thread and move it to
  struct ublk_thread_info

- Remove struct ublk_thread array from struct ublk_dev, reducing memory
  footprint

- Define struct ublk_thread as local variable in __ublk_io_handler_fn()
  instead of accessing it from dev->threads[]

- Extract main IO handling logic into __ublk_io_handler_fn() which is
  marked as noinline

- Move CPU affinity setup to ublk_io_handler_fn() before calling
  __ublk_io_handler_fn()

- Update ublk_thread_set_sched_affinity() to take struct ublk_thread_info *
  instead of struct ublk_thread *, and use pthread_setaffinity_np()
  instead of sched_setaffinity()

- Reorder struct ublk_thread fields to group related state together

This change makes each thread's ublk_thread structure truly local to
the thread, improving cache locality and reducing memory usage.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
index 062537ab89764d9560a71e5d5063959212a181c8..f8fa102a627fd702aee1f1cbcbd47114d79d1f77 100644 (file)
--- a/tools/testing/selftests/ublk/kublk.c
+++ b/tools/testing/selftests/ublk/kublk.c
@@ -836,62 +836,70 @@ static int ublk_process_io(struct ublk_thread *t)
        return reapped;
 }
 
-static void ublk_thread_set_sched_affinity(const struct ublk_thread *t,
-               cpu_set_t *cpuset)
-{
-       if (pthread_setaffinity_np(pthread_self(), sizeof(*cpuset), cpuset) < 0)
-               ublk_err("ublk dev %u thread %u set affinity failed",
-                               t->dev->dev_info.dev_id, t->idx);
-}
-
 struct ublk_thread_info {
        struct ublk_dev         *dev;
+       pthread_t               thread;
        unsigned                idx;
        sem_t                   *ready;
        cpu_set_t               *affinity;
        unsigned long long      extra_flags;
 };
 
-static void *ublk_io_handler_fn(void *data)
+static void ublk_thread_set_sched_affinity(const struct ublk_thread_info *info)
 {
-       struct ublk_thread_info *info = data;
-       struct ublk_thread *t = &info->dev->threads[info->idx];
+       if (pthread_setaffinity_np(pthread_self(), sizeof(*info->affinity), info->affinity) < 0)
+               ublk_err("ublk dev %u thread %u set affinity failed",
+                               info->dev->dev_info.dev_id, info->idx);
+}
+
+static __attribute__((noinline)) int __ublk_io_handler_fn(struct ublk_thread_info *info)
+{
+       struct ublk_thread t = {
+               .dev = info->dev,
+               .idx = info->idx,
+       };
        int dev_id = info->dev->dev_info.dev_id;
        int ret;
 
-       t->dev = info->dev;
-       t->idx = info->idx;
-
-       /*
-        * IO perf is sensitive with queue pthread affinity on NUMA machine
-        *
-        * Set sched_affinity at beginning, so following allocated memory/pages
-        * could be CPU/NUMA aware.
-        */
-       if (info->affinity)
-               ublk_thread_set_sched_affinity(t, info->affinity);
-
-       ret = ublk_thread_init(t, info->extra_flags);
+       ret = ublk_thread_init(&t, info->extra_flags);
        if (ret) {
                ublk_err("ublk dev %d thread %u init failed\n",
-                               dev_id, t->idx);
-               return NULL;
+                               dev_id, t.idx);
+               return ret;
        }
        sem_post(info->ready);
 
        ublk_dbg(UBLK_DBG_THREAD, "tid %d: ublk dev %d thread %u started\n",
-                       gettid(), dev_id, t->idx);
+                       gettid(), dev_id, t.idx);
 
        /* submit all io commands to ublk driver */
-       ublk_submit_fetch_commands(t);
+       ublk_submit_fetch_commands(&t);
        do {
-               if (ublk_process_io(t) < 0)
+               if (ublk_process_io(&t) < 0)
                        break;
        } while (1);
 
        ublk_dbg(UBLK_DBG_THREAD, "tid %d: ublk dev %d thread %d exiting\n",
-                gettid(), dev_id, t->idx);
-       ublk_thread_deinit(t);
+                gettid(), dev_id, t.idx);
+       ublk_thread_deinit(&t);
+       return 0;
+}
+
+static void *ublk_io_handler_fn(void *data)
+{
+       struct ublk_thread_info *info = data;
+
+       /*
+        * IO perf is sensitive with queue pthread affinity on NUMA machine
+        *
+        * Set sched_affinity at beginning, so following allocated memory/pages
+        * could be CPU/NUMA aware.
+        */
+       if (info->affinity)
+               ublk_thread_set_sched_affinity(info);
+
+       __ublk_io_handler_fn(info);
+
        return NULL;
 }
 
@@ -989,14 +997,13 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev)
                 */
                if (dev->nthreads == dinfo->nr_hw_queues)
                        tinfo[i].affinity = &affinity_buf[i];
-               pthread_create(&dev->threads[i].thread, NULL,
+               pthread_create(&tinfo[i].thread, NULL,
                                ublk_io_handler_fn,
                                &tinfo[i]);
        }
 
        for (i = 0; i < dev->nthreads; i++)
                sem_wait(&ready);
-       free(tinfo);
        free(affinity_buf);
 
        /* everything is fine now, start us */
@@ -1019,7 +1026,8 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev)
 
        /* wait until we are terminated */
        for (i = 0; i < dev->nthreads; i++)
-               pthread_join(dev->threads[i].thread, &thread_ret);
+               pthread_join(tinfo[i].thread, &thread_ret);
+       free(tinfo);
  fail:
        for (i = 0; i < dinfo->nr_hw_queues; i++)
                ublk_queue_deinit(&dev->q[i]);

diff --git a/tools/testing/selftests/ublk/kublk.h b/tools/testing/selftests/ublk/kublk.h
index 5e55484fb0aa26f6bdddea07723f9af0019c56be..fe42705c6d42dc593df042181fd4bff461e34576 100644 (file)
--- a/tools/testing/selftests/ublk/kublk.h
+++ b/tools/testing/selftests/ublk/kublk.h
@@ -175,23 +175,20 @@ struct ublk_queue {
 
 struct ublk_thread {
        struct ublk_dev *dev;
-       struct io_uring ring;
-       unsigned int cmd_inflight;
-       unsigned int io_inflight;
-
-       pthread_t thread;
        unsigned idx;
 
 #define UBLKS_T_STOPPING       (1U << 0)
 #define UBLKS_T_IDLE   (1U << 1)
        unsigned state;
+       unsigned int cmd_inflight;
+       unsigned int io_inflight;
+       struct io_uring ring;
 };
 
 struct ublk_dev {
        struct ublk_tgt tgt;
        struct ublksrv_ctrl_dev_info  dev_info;
        struct ublk_queue q[UBLK_MAX_QUEUES];
-       struct ublk_thread threads[UBLK_MAX_THREADS];
        unsigned nthreads;
        unsigned per_io_tasks;