From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Sat, 20 Aug 2011 00:44:21 +0000 (-0400)
Subject: Add wakeup on subbuffer delivery
X-Git-Tag: v1.9.1~298
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=5d61a504c6d395914d78f97e82f6fd0fdf0f98a0;p=lttng-ust.git

Add wakeup on subbuffer delivery

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/libringbuffer/frontend_internal.h b/libringbuffer/frontend_internal.h
index 73b44726..c60affe0 100644
--- a/libringbuffer/frontend_internal.h
+++ b/libringbuffer/frontend_internal.h
@@ -378,8 +378,19 @@ void lib_ring_buffer_check_deliver(const struct lib_ring_buffer_config *config,
 			if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER
 			    && uatomic_read(&buf->active_readers)
 			    && lib_ring_buffer_poll_deliver(config, buf, chan, handle)) {
-				//wake_up_interruptible(&buf->read_wait);
-				//wake_up_interruptible(&chan->read_wait);
+				int wakeup_fd = shm_get_wakeup_fd(handle, &buf->self._ref);
+
+				if (wakeup_fd >= 0) {
+					int ret;
+					/*
+					 * Wake-up the other end by
+					 * writing a null byte in the
+					 * pipe (non-blocking).
+					 */
+					do {
+						ret = write(wakeup_fd, "", 1);
+					} while (ret == -1L && errno == EINTR);
+				}
 			}
 
 		}
diff --git a/libringbuffer/frontend_types.h b/libringbuffer/frontend_types.h
index 974f782e..ad7848c8 100644
--- a/libringbuffer/frontend_types.h
+++ b/libringbuffer/frontend_types.h
@@ -103,6 +103,8 @@ struct lib_ring_buffer {
 	int get_subbuf:1;		/* Sub-buffer being held by reader */
 	int switch_timer_enabled:1;	/* Protected by ring_buffer_nohz_lock */
 	int read_timer_enabled:1;	/* Protected by ring_buffer_nohz_lock */
+	/* shmp pointer to self */
+	DECLARE_SHMP(struct lib_ring_buffer, self);
 } ____cacheline_aligned;
 
 static inline
diff --git a/libringbuffer/ring_buffer_backend.c b/libringbuffer/ring_buffer_backend.c
index badde80f..18dd1b01 100644
--- a/libringbuffer/ring_buffer_backend.c
+++ b/libringbuffer/ring_buffer_backend.c
@@ -283,6 +283,7 @@ int channel_backend_init(struct channel_backend *chanb,
 			buf = shmp(handle, chanb->buf[i].shmp);
 			if (!buf)
 				goto end;
+			set_shmp(buf->self, chanb->buf[i].shmp._ref);
 			ret = lib_ring_buffer_create(buf, chanb, i,
 					handle, shmobj);
 			if (ret)
diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index 8f158e2f..6a77af64 100644
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -49,6 +49,12 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
 			goto error_fcntl;
 		}
 	}
+	/* The write end of the pipe needs to be non-blocking */
+	ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK);
+	if (ret < 0) {
+		PERROR("fcntl");
+		goto error_fcntl;
+	}
 	*obj->wait_fd = *waitfd;
 
 	/* shm_fd: create shm */
diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index d370375b..008c5c41 100644
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -68,4 +68,33 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
 struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
 void align_shm(struct shm_object *obj, size_t align);
 
+static inline
+int shm_get_wakeup_fd(struct shm_handle *handle, struct shm_ref *ref)
+{
+	struct shm_object_table *table = handle->table;
+	struct shm_object *obj;
+	size_t index;
+
+	index = (size_t) ref->index;
+	if (unlikely(index >= table->allocated_len))
+		return -EPERM;
+	obj = &table->objects[index];
+	return obj->wait_fd[1];
+
+}
+
+static inline
+int shm_get_wait_fd(struct shm_handle *handle, struct shm_ref *ref)
+{
+	struct shm_object_table *table = handle->table;
+	struct shm_object *obj;
+	size_t index;
+
+	index = (size_t) ref->index;
+	if (unlikely(index >= table->allocated_len))
+		return -EPERM;
+	obj = &table->objects[index];
+	return obj->wait_fd[0];
+}
+
 #endif /* _LIBRINGBUFFER_SHM_H */
diff --git a/libust/ltt-ring-buffer-client.h b/libust/ltt-ring-buffer-client.h
index d71d3861..e4845642 100644
--- a/libust/ltt-ring-buffer-client.h
+++ b/libust/ltt-ring-buffer-client.h
@@ -362,13 +362,13 @@ static const struct lib_ring_buffer_config client_config = {
 
 	.tsc_bits = 32,
 	.alloc = RING_BUFFER_ALLOC_PER_CPU,
-	.sync = RING_BUFFER_SYNC_PER_CPU,
+	.sync = RING_BUFFER_SYNC_GLOBAL,
 	.mode = RING_BUFFER_MODE_TEMPLATE,
 	.backend = RING_BUFFER_PAGE,
-	.output = RING_BUFFER_SPLICE,
+	.output = RING_BUFFER_MMAP,
 	.oops = RING_BUFFER_OOPS_CONSISTENCY,
-	.ipi = RING_BUFFER_IPI_BARRIER,
-	.wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
+	.ipi = RING_BUFFER_NO_IPI_BARRIER,
+	.wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 };
 
 static
diff --git a/libust/ltt-ring-buffer-metadata-client.h b/libust/ltt-ring-buffer-metadata-client.h
index 88716a26..ef70a9f0 100644
--- a/libust/ltt-ring-buffer-metadata-client.h
+++ b/libust/ltt-ring-buffer-metadata-client.h
@@ -149,10 +149,10 @@ static const struct lib_ring_buffer_config client_config = {
 	.sync = RING_BUFFER_SYNC_GLOBAL,
 	.mode = RING_BUFFER_MODE_TEMPLATE,
 	.backend = RING_BUFFER_PAGE,
-	.output = RING_BUFFER_SPLICE,
+	.output = RING_BUFFER_MMAP,
 	.oops = RING_BUFFER_OOPS_CONSISTENCY,
-	.ipi = RING_BUFFER_IPI_BARRIER,
-	.wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
+	.ipi = RING_BUFFER_NO_IPI_BARRIER,
+	.wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 };
 
 static