rte_rcu_qsbr_get_memsize API is introduced. This will allow the user
to controll the amount of memory used based on the maximum
number of threads present in the application.
Signed-off-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
---
lib/librte_rcu/rte_rcu_qsbr.c | 51 ++++++++++++---
lib/librte_rcu/rte_rcu_qsbr.h | 118 +++++++++++++++++++++-------------
2 files changed, 118 insertions(+), 51 deletions(-)
diff --git a/lib/librte_rcu/rte_rcu_qsbr.c b/lib/librte_rcu/rte_rcu_qsbr.c
index 3c2577ee2..02464fdba 100644
--- a/lib/librte_rcu/rte_rcu_qsbr.c
+++ b/lib/librte_rcu/rte_rcu_qsbr.c
@@ -21,11 +21,39 @@
#include "rte_rcu_qsbr.h"
+/* Get the memory size of QSBR variable */
+unsigned int __rte_experimental
+rte_rcu_qsbr_get_memsize(uint32_t max_threads)
+{
+ int n;
+ ssize_t sz;
+
+ RTE_ASSERT(max_threads == 0);
+
+ sz = sizeof(struct rte_rcu_qsbr);
+
+ /* Add the size of the registered thread ID bitmap array */
+ n = RTE_ALIGN(max_threads, RTE_QSBR_THRID_ARRAY_ELM_SIZE);
+ sz += RTE_QSBR_THRID_ARRAY_SIZE(n);
+
+ /* Add the size of quiescent state counter array */
+ sz += sizeof(struct rte_rcu_qsbr_cnt) * max_threads;
+
+ return RTE_ALIGN(sz, RTE_CACHE_LINE_SIZE);
+}
+
/* Initialize a quiescent state variable */
void __rte_experimental
-rte_rcu_qsbr_init(struct rte_rcu_qsbr *v)
+rte_rcu_qsbr_init(struct rte_rcu_qsbr *v, uint32_t max_threads)
{
- memset(v, 0, sizeof(struct rte_rcu_qsbr));
+ RTE_ASSERT(v == NULL);
+
+ memset(v, 0, rte_rcu_qsbr_get_memsize(max_threads));
+ v->m_threads = max_threads;
+ v->ma_threads = RTE_ALIGN(max_threads, RTE_QSBR_THRID_ARRAY_ELM_SIZE);
+
+ v->num_elems = v->ma_threads/RTE_QSBR_THRID_ARRAY_ELM_SIZE;
+ v->thrid_array_size = RTE_QSBR_THRID_ARRAY_SIZE(v->ma_threads);
}
/* Dump the details of a single quiescent state variable to a file. */
@@ -39,9 +67,15 @@ rte_rcu_qsbr_dump(FILE *f, struct rte_rcu_qsbr *v)
fprintf(f, "\nQuiescent State Variable @%p\n", v);
+ fprintf(f, " QS variable memory size = %u\n",
+ rte_rcu_qsbr_get_memsize(v->m_threads));
+ fprintf(f, " Given # max threads = %u\n", v->m_threads);
+ fprintf(f, " Adjusted # max threads = %u\n", v->ma_threads);
+
fprintf(f, " Registered thread ID mask = 0x");
- for (i = 0; i < RTE_QSBR_BIT_MAP_ELEMS; i++)
- fprintf(f, "%lx", __atomic_load_n(&v->reg_thread_id[i],
+ for (i = 0; i < v->num_elems; i++)
+ fprintf(f, "%lx", __atomic_load_n(
+ RTE_QSBR_THRID_ARRAY_ELM(v, i),
__ATOMIC_ACQUIRE));
fprintf(f, "\n");
@@ -49,14 +83,15 @@ rte_rcu_qsbr_dump(FILE *f, struct rte_rcu_qsbr *v)
__atomic_load_n(&v->token, __ATOMIC_ACQUIRE));
fprintf(f, "Quiescent State Counts for readers:\n");
- for (i = 0; i < RTE_QSBR_BIT_MAP_ELEMS; i++) {
- bmap = __atomic_load_n(&v->reg_thread_id[i],
+ for (i = 0; i < v->num_elems; i++) {
+ bmap = __atomic_load_n(RTE_QSBR_THRID_ARRAY_ELM(v, i),
__ATOMIC_ACQUIRE);
while (bmap) {
t = __builtin_ctzl(bmap);
fprintf(f, "thread ID = %d, count = %lu\n", t,
- __atomic_load_n(&v->w[i].cnt,
- __ATOMIC_RELAXED));
+ __atomic_load_n(
+ &RTE_QSBR_CNT_ARRAY_ELM(v, i)->cnt,
+ __ATOMIC_RELAXED));
bmap &= ~(1UL << t);
}
}
diff --git a/lib/librte_rcu/rte_rcu_qsbr.h b/lib/librte_rcu/rte_rcu_qsbr.h
index 53e00488b..21fa2c198 100644
--- a/lib/librte_rcu/rte_rcu_qsbr.h
+++ b/lib/librte_rcu/rte_rcu_qsbr.h
@@ -29,46 +29,71 @@ extern "C" {
#include <rte_lcore.h>
#include <rte_debug.h>
-/**< Maximum number of reader threads supported. */
-#define RTE_RCU_MAX_THREADS 128
-
-#if !RTE_IS_POWER_OF_2(RTE_RCU_MAX_THREADS)
-#error RTE_RCU_MAX_THREADS must be a power of 2
-#endif
-
-/**< Number of array elements required for the bit-map */
-#define RTE_QSBR_BIT_MAP_ELEMS (RTE_RCU_MAX_THREADS/(sizeof(uint64_t) * 8))
-
-/* Thread IDs are stored as a bitmap of 64b element array. Given thread id
- * needs to be converted to index into the array and the id within
- * the array element.
+/* Registered thread IDs are stored as a bitmap of 64b element array.
+ * Given thread id needs to be converted to index into the array and
+ * the id within the array element.
+ */
+/* Thread ID array size
+ * @param ma_threads
+ * num of threads aligned to 64
*/
-#define RTE_QSBR_THR_INDEX_SHIFT 6
-#define RTE_QSBR_THR_ID_MASK 0x3f
+#define RTE_QSBR_THRID_ARRAY_SIZE(ma_threads) \
+ RTE_ALIGN((ma_threads) >> 3, RTE_CACHE_LINE_SIZE)
+#define RTE_QSBR_THRID_ARRAY_ELM_SIZE (sizeof(uint64_t) * 8)
+#define RTE_QSBR_THRID_ARRAY_ELM(v, i) ((uint64_t *)(v + 1) + i)
+#define RTE_QSBR_THRID_INDEX_SHIFT 6
+#define RTE_QSBR_THRID_MASK 0x3f
/* Worker thread counter */
struct rte_rcu_qsbr_cnt {
uint64_t cnt; /**< Quiescent state counter. */
} __rte_cache_aligned;
+#define RTE_QSBR_CNT_ARRAY_ELM(v, i) ((struct rte_rcu_qsbr_cnt *) \
+ ((uint8_t *)(v + 1) + v->thrid_array_size) + i)
+
/**
* RTE thread Quiescent State structure.
+ * The following data, which is dependent on the maximum number of
+ * threads using this variable, is stored in memory immediately
+ * following this structure.
+ *
+ * 1) registered thread ID bitmap array
+ * This is a uint64_t array enough to hold 'ma_threads' number
+ * of thread IDs.
+ * 2) quiescent state counter array
+ * This is an array of 'struct rte_rcu_qsbr_cnt' with
+ * 'm_threads' number of elements.
*/
struct rte_rcu_qsbr {
- uint64_t reg_thread_id[RTE_QSBR_BIT_MAP_ELEMS] __rte_cache_aligned;
- /**< Registered reader thread IDs - reader threads reporting
- * on this QS variable represented in a bit map.
- */
-
uint64_t token __rte_cache_aligned;
/**< Counter to allow for multiple simultaneous QS queries */
- struct rte_rcu_qsbr_cnt w[RTE_RCU_MAX_THREADS] __rte_cache_aligned;
- /**< QS counter for each reader thread, counts upto
- * current value of token.
- */
+ uint32_t thrid_array_size __rte_cache_aligned;
+ /**< Registered thread ID bitmap array size in bytes */
+ uint32_t num_elems;
+ /**< Number of elements in the thread ID array */
+
+ uint32_t m_threads;
+ /**< Maximum number of threads this RCU variable will use */
+ uint32_t ma_threads;
+ /**< Maximum number of threads aligned to 32 */
} __rte_cache_aligned;
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Return the size of the memory occupied by a Quiescent State (QS) variable.
+ *
+ * @param max_threads
+ * Maximum number of threads reporting QS on this variable.
+ * @return
+ * Size of memory in bytes required for this QS variable.
+ */
+unsigned int __rte_experimental
+rte_rcu_qsbr_get_memsize(uint32_t max_threads);
+
/**
* @warning
* @b EXPERIMENTAL: this API may change without prior notice
@@ -77,10 +102,12 @@ struct rte_rcu_qsbr {
*
* @param v
* QS variable
+ * @param max_threads
+ * Maximum number of threads reporting QS on this variable.
*
*/
void __rte_experimental
-rte_rcu_qsbr_init(struct rte_rcu_qsbr *v);
+rte_rcu_qsbr_init(struct rte_rcu_qsbr *v, uint32_t max_threads);
/**
* @warning
@@ -108,24 +135,25 @@ rte_rcu_qsbr_register_thread(struct rte_rcu_qsbr *v,
unsigned int thread_id)
{
unsigned int i, id;
- RTE_ASSERT(v == NULL || thread_id >= RTE_RCU_MAX_THREADS);
+ RTE_ASSERT(v == NULL || thread_id >= v->max_threads);
- id = thread_id & RTE_QSBR_THR_ID_MASK;
- i = thread_id >> RTE_QSBR_THR_INDEX_SHIFT;
+ id = thread_id & RTE_QSBR_THRID_MASK;
+ i = thread_id >> RTE_QSBR_THRID_INDEX_SHIFT;
/* Worker thread has to count the quiescent states
* only from the current value of token.
* __atomic_store_n(cnt, __ATOMIC_RELAXED) is used to ensure
* 'cnt' (64b) is accessed atomically.
*/
- __atomic_store_n(&v->w[thread_id].cnt,
+ __atomic_store_n(&RTE_QSBR_CNT_ARRAY_ELM(v, thread_id)->cnt,
__atomic_load_n(&v->token, __ATOMIC_ACQUIRE),
__ATOMIC_RELAXED);
/* Release the store to initial TQS count so that readers
* can use it immediately after this function returns.
*/
- __atomic_fetch_or(&v->reg_thread_id[i], 1UL << id, __ATOMIC_RELEASE);
+ __atomic_fetch_or(RTE_QSBR_THRID_ARRAY_ELM(v, i),
+ 1UL << id, __ATOMIC_RELEASE);
}
/**
@@ -151,16 +179,16 @@ rte_rcu_qsbr_unregister_thread(struct rte_rcu_qsbr *v,
unsigned int thread_id)
{
unsigned int i, id;
- RTE_ASSERT(v == NULL || thread_id >= RTE_RCU_MAX_THREADS);
+ RTE_ASSERT(v == NULL || thread_id >= v->max_threads);
- id = thread_id & RTE_QSBR_THR_ID_MASK;
- i = thread_id >> RTE_QSBR_THR_INDEX_SHIFT;
+ id = thread_id & RTE_QSBR_THRID_MASK;
+ i = thread_id >> RTE_QSBR_THRID_INDEX_SHIFT;
/* Make sure the removal of the thread from the list of
* reporting threads is visible before the thread
* does anything else.
*/
- __atomic_fetch_and(&v->reg_thread_id[i],
+ __atomic_fetch_and(RTE_QSBR_THRID_ARRAY_ELM(v, i),
~(1UL << id), __ATOMIC_RELEASE);
}
@@ -212,7 +240,7 @@ rte_rcu_qsbr_update(struct rte_rcu_qsbr *v, unsigned int
thread_id)
{
uint64_t t;
- RTE_ASSERT(v == NULL || thread_id >= RTE_RCU_MAX_THREADS);
+ RTE_ASSERT(v == NULL || thread_id >= v->max_threads);
/* Load the token before the reader thread loads any other
* (lock-free) data structure. This ensures that updates
@@ -228,8 +256,10 @@ rte_rcu_qsbr_update(struct rte_rcu_qsbr *v, unsigned int
thread_id)
* Copy the current token value. This will end grace period
* of multiple concurrent writers.
*/
- if (__atomic_load_n(&v->w[thread_id].cnt, __ATOMIC_RELAXED) != t)
- __atomic_store_n(&v->w[thread_id].cnt, t, __ATOMIC_RELAXED);
+ if (__atomic_load_n(&RTE_QSBR_CNT_ARRAY_ELM(v, thread_id)->cnt,
+ __ATOMIC_RELAXED) != t)
+ __atomic_store_n(&RTE_QSBR_CNT_ARRAY_ELM(v, thread_id)->cnt,
+ t, __ATOMIC_RELAXED);
}
/**
@@ -268,18 +298,20 @@ rte_rcu_qsbr_check(struct rte_rcu_qsbr *v, uint64_t t,
bool wait)
/* Load the current registered thread bit map before
* loading the reader thread quiescent state counters.
*/
- bmap = __atomic_load_n(&v->reg_thread_id[i], __ATOMIC_ACQUIRE);
- id = i << RTE_QSBR_THR_INDEX_SHIFT;
+ bmap = __atomic_load_n(RTE_QSBR_THRID_ARRAY_ELM(v, i),
+ __ATOMIC_ACQUIRE);
+ id = i << RTE_QSBR_THRID_INDEX_SHIFT;
while (bmap) {
j = __builtin_ctzl(bmap);
-/* printf ("Status check: token = %lu, wait = %d, Bit Map = 0x%x, Thread ID =
%d\n", t, wait, bmap, id+j); */
+/* printf ("Status check: token = %lu, wait = %d, Bit Map = 0x%lx, Thread ID =
%d\n", t, wait, bmap, id+j); */
/* __atomic_load_n(cnt, __ATOMIC_RELAXED)
* is used to ensure 'cnt' (64b) is accessed
* atomically.
*/
- if (unlikely(__atomic_load_n(&v->w[id + j].cnt,
+ if (unlikely(__atomic_load_n(
+ &RTE_QSBR_CNT_ARRAY_ELM(v, id + j)->cnt,
__ATOMIC_RELAXED) < t)) {
/* printf ("Status not in QS: token = %lu, Wait = %d, Thread QS cnt = %lu,
Thread ID = %d\n", t, wait, RTE_QSBR_CNT_ARRAY_ELM(v, id + j)->cnt, id+j); */
@@ -292,7 +324,7 @@ rte_rcu_qsbr_check(struct rte_rcu_qsbr *v, uint64_t t, bool
wait)
* Re-read the bitmap.
*/
bmap = __atomic_load_n(
- &v->reg_thread_id[i],
+ RTE_QSBR_THRID_ARRAY_ELM(v, i),
__ATOMIC_ACQUIRE);
continue;
@@ -302,7 +334,7 @@ rte_rcu_qsbr_check(struct rte_rcu_qsbr *v, uint64_t t, bool
wait)
}
i++;
- } while (i < RTE_QSBR_BIT_MAP_ELEMS);
+ } while (i < v->num_elems);
return 1;
}
--
2.17.1
