svm: add support for eventfd signaling to queue
Support the use of eventfds to signal queue updates between consumer
and producer pairs.
Change-Id: Idb6133be2b731fff78ed520daf9d2e0399642aab
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/svm/message_queue.c b/src/svm/message_queue.c
index 1b2d2e1..e97cab8 100644
--- a/src/svm/message_queue.c
+++ b/src/svm/message_queue.c
@@ -39,12 +39,12 @@
svm_msg_q_alloc (svm_msg_q_cfg_t * cfg)
{
svm_msg_q_ring_cfg_t *ring_cfg;
+ uword rings_sz = 0, mq_sz;
svm_msg_q_ring_t *ring;
u8 *base, *rings_ptr;
- uword rings_sz = 0;
vec_header_t *vh;
+ u32 vec_sz, q_sz;
svm_msg_q_t *mq;
- u32 vec_sz;
int i;
ASSERT (cfg);
@@ -58,13 +58,17 @@
rings_sz += (uword) ring_cfg->nitems * ring_cfg->elsize;
}
- base = clib_mem_alloc_aligned (sizeof (svm_msg_q_t) + vec_sz + rings_sz,
- CLIB_CACHE_LINE_BYTES);
+ q_sz = sizeof (svm_queue_t) + cfg->q_nitems * sizeof (svm_msg_q_msg_t);
+ mq_sz = sizeof (svm_msg_q_t) + vec_sz + rings_sz + q_sz;
+ base = clib_mem_alloc_aligned (mq_sz, CLIB_CACHE_LINE_BYTES);
if (!base)
return 0;
mq = (svm_msg_q_t *) base;
- vh = (vec_header_t *) (base + sizeof (svm_msg_q_t));
+ mq->q = svm_queue_init (base + sizeof (svm_msg_q_t), cfg->q_nitems,
+ sizeof (svm_msg_q_msg_t));
+ mq->q->consumer_pid = cfg->consumer_pid;
+ vh = (vec_header_t *) ((u8 *) mq->q + q_sz);
vh->len = cfg->n_rings;
mq->rings = (svm_msg_q_ring_t *) (vh + 1);
rings_ptr = (u8 *) mq->rings + vec_sz;
@@ -82,8 +86,6 @@
rings_ptr += (uword) ring->nitems * ring->elsize;
}
}
- mq->q = svm_queue_init (cfg->q_nitems, sizeof (svm_msg_q_msg_t),
- cfg->consumer_pid, 0);
return mq;
}
diff --git a/src/svm/queue.c b/src/svm/queue.c
index 8e18f58..0fa1fe9 100644
--- a/src/svm/queue.c
+++ b/src/svm/queue.c
@@ -27,42 +27,21 @@
#include <vppinfra/cache.h>
#include <svm/queue.h>
#include <vppinfra/time.h>
-#include <signal.h>
-/*
- * svm_queue_init
- *
- * nels = number of elements on the queue
- * elsize = element size, presumably 4 and cacheline-size will
- * be popular choices.
- * pid = consumer pid
- *
- * The idea is to call this function in the queue consumer,
- * and e-mail the queue pointer to the producer(s).
- *
- * The vpp process / main thread allocates one of these
- * at startup; its main input queue. The vpp main input queue
- * has a pointer to it in the shared memory segment header.
- *
- * You probably want to be on an svm data heap before calling this
- * function.
- */
svm_queue_t *
-svm_queue_init (int nels,
- int elsize, int consumer_pid, int signal_when_queue_non_empty)
+svm_queue_init (void *base, int nels, int elsize)
{
svm_queue_t *q;
pthread_mutexattr_t attr;
pthread_condattr_t cattr;
- q = clib_mem_alloc_aligned (sizeof (svm_queue_t)
- + nels * elsize, CLIB_CACHE_LINE_BYTES);
+ q = (svm_queue_t *) base;
memset (q, 0, sizeof (*q));
q->elsize = elsize;
q->maxsize = nels;
- q->consumer_pid = consumer_pid;
- q->signal_when_queue_non_empty = signal_when_queue_non_empty;
+ q->producer_evtfd = -1;
+ q->consumer_evtfd = -1;
memset (&attr, 0, sizeof (attr));
memset (&cattr, 0, sizeof (cattr));
@@ -88,6 +67,20 @@
return (q);
}
+svm_queue_t *
+svm_queue_alloc_and_init (int nels, int elsize, int consumer_pid)
+{
+ svm_queue_t *q;
+
+ q = clib_mem_alloc_aligned (sizeof (svm_queue_t)
+ + nels * elsize, CLIB_CACHE_LINE_BYTES);
+ memset (q, 0, sizeof (*q));
+ q = svm_queue_init (q, nels, elsize);
+ q->consumer_pid = consumer_pid;
+
+ return q;
+}
+
/*
* svm_queue_free
*/
@@ -117,6 +110,23 @@
return q->cursize == q->maxsize;
}
+static inline void
+svm_queue_send_signal (svm_queue_t * q, u8 is_prod)
+{
+ if (q->producer_evtfd == -1)
+ {
+ (void) pthread_cond_broadcast (&q->condvar);
+ }
+ else
+ {
+ int __clib_unused rv, fd;
+ u64 data = 1;
+ ASSERT (q->consumer_evtfd != -1);
+ fd = is_prod ? q->producer_evtfd : q->consumer_evtfd;
+ rv = write (fd, &data, sizeof (data));
+ }
+}
+
/*
* svm_queue_add_nolock
*/
@@ -146,11 +156,7 @@
q->tail = 0;
if (need_broadcast)
- {
- (void) pthread_cond_broadcast (&q->condvar);
- if (q->signal_when_queue_non_empty)
- kill (q->consumer_pid, q->signal_when_queue_non_empty);
- }
+ svm_queue_send_signal (q, 1);
return 0;
}
@@ -212,11 +218,8 @@
q->tail = 0;
if (need_broadcast)
- {
- (void) pthread_cond_broadcast (&q->condvar);
- if (q->signal_when_queue_non_empty)
- kill (q->consumer_pid, q->signal_when_queue_non_empty);
- }
+ svm_queue_send_signal (q, 1);
+
pthread_mutex_unlock (&q->mutex);
return 0;
@@ -276,11 +279,8 @@
q->tail = 0;
if (need_broadcast)
- {
- (void) pthread_cond_broadcast (&q->condvar);
- if (q->signal_when_queue_non_empty)
- kill (q->consumer_pid, q->signal_when_queue_non_empty);
- }
+ svm_queue_send_signal (q, 1);
+
pthread_mutex_unlock (&q->mutex);
return 0;
@@ -353,7 +353,7 @@
q->head = 0;
if (need_broadcast)
- (void) pthread_cond_broadcast (&q->condvar);
+ svm_queue_send_signal (q, 0);
pthread_mutex_unlock (&q->mutex);
@@ -385,7 +385,7 @@
pthread_mutex_unlock (&q->mutex);
if (need_broadcast)
- (void) pthread_cond_broadcast (&q->condvar);
+ svm_queue_send_signal (q, 0);
return 0;
}
@@ -410,6 +410,18 @@
return 0;
}
+void
+svm_queue_set_producer_event_fd (svm_queue_t * q, int fd)
+{
+ q->producer_evtfd = fd;
+}
+
+void
+svm_queue_set_consumer_event_fd (svm_queue_t * q, int fd)
+{
+ q->consumer_evtfd = fd;
+}
+
/*
* fd.io coding-style-patch-verification: ON
*
diff --git a/src/svm/queue.h b/src/svm/queue.h
index 68a63d7..75e63a4 100644
--- a/src/svm/queue.h
+++ b/src/svm/queue.h
@@ -32,32 +32,43 @@
int maxsize;
int elsize;
int consumer_pid;
- int signal_when_queue_non_empty;
+ int producer_evtfd;
+ int consumer_evtfd;
char data[0];
} svm_queue_t;
typedef enum
{
- /**
- * blocking call
- */
- SVM_Q_WAIT = 0,
-
- /**
- * non-blocking call
- */
- SVM_Q_NOWAIT,
-
- /**
- * blocking call, return on signal or time-out
- */
- SVM_Q_TIMEDWAIT,
+ SVM_Q_WAIT = 0, /**< blocking call - must be used only in combination
+ with condvars */
+ SVM_Q_NOWAIT, /**< non-blocking call - works with both condvar and
+ eventfd signaling */
+ SVM_Q_TIMEDWAIT, /**< blocking call, returns on signal or time-out -
+ must be used only in combination with condvars */
} svm_q_conditional_wait_t;
-svm_queue_t *svm_queue_init (int nels,
- int elsize,
- int consumer_pid,
- int signal_when_queue_non_empty);
+/**
+ * Allocate and initialize svm queue
+ *
+ * @param nels number of elements on the queue
+ * @param elsize element size, presumably 4 and cacheline-size will
+ * be popular choices.
+ * @param pid consumer pid
+ * @return a newly initialized svm queue
+ *
+ * The idea is to call this function in the queue consumer,
+ * and e-mail the queue pointer to the producer(s).
+ *
+ * The vpp process / main thread allocates one of these
+ * at startup; its main input queue. The vpp main input queue
+ * has a pointer to it in the shared memory segment header.
+ *
+ * You probably want to be on an svm data heap before calling this
+ * function.
+ */
+svm_queue_t *svm_queue_alloc_and_init (int nels, int elsize,
+ int consumer_pid);
+svm_queue_t *svm_queue_init (void *base, int nels, int elsize);
void svm_queue_free (svm_queue_t * q);
int svm_queue_add (svm_queue_t * q, u8 * elem, int nowait);
int svm_queue_add2 (svm_queue_t * q, u8 * elem, u8 * elem2, int nowait);
@@ -77,6 +88,25 @@
*/
void svm_queue_add_raw (svm_queue_t * q, u8 * elem);
+/**
+ * Set producer's event fd
+ *
+ * When the producer must generate an event it writes 1 to the provided fd.
+ * Once this is set, condvars are not used anymore for signaling.
+ */
+void svm_queue_set_producer_event_fd (svm_queue_t * q, int fd);
+
+/**
+ * Set consumer's event fd
+ *
+ * When the consumer must generate an event it writes 1 to the provided fd.
+ * Although in practice the two fds point to the same underlying file
+ * description, because the producer and consumer are different processes
+ * the descriptors will be different. It's the caller's responsibility to
+ * ensure the file descriptors are properly exchanged between the two peers.
+ */
+void svm_queue_set_consumer_event_fd (svm_queue_t * q, int fd);
+
/*
* DEPRECATED please use svm_queue_t instead
*/
diff --git a/src/svm/test_svm_message_queue.c b/src/svm/test_svm_message_queue.c
index 758163f..9441c59 100644
--- a/src/svm/test_svm_message_queue.c
+++ b/src/svm/test_svm_message_queue.c
@@ -169,6 +169,7 @@
unformat_input_t i;
int r;
+ clib_mem_init_thread_safe (0, 256 << 20);
unformat_init_command_line (&i, argv);
r = test_svm_message_queue (&i);
unformat_free (&i);