The RED scheduler used its own random number generator which was
weak and buggy. Change standard rte_rand() which has better
randomness and is thread safe.
There is no prior deprecation notice for relatedd symbols. They were
never meant to be part of the API: rte_fast_rand() is the internal
generator of the dropper and the two variables are its state, all
exposed only because the drop test is inline in rte_red.h.
Fixes: de3cfa2c9823 ("sched: initial import")
Signed-off-by: Stephen Hemminger <[email protected]>
---
doc/guides/rel_notes/release_26_11.rst | 3 +++
lib/sched/rte_red.c | 9 +--------
lib/sched/rte_red.h | 26 ++------------------------
3 files changed, 6 insertions(+), 32 deletions(-)
diff --git a/doc/guides/rel_notes/release_26_11.rst
b/doc/guides/rel_notes/release_26_11.rst
index 88c06025b0..d4a3a7e7f2 100644
--- a/doc/guides/rel_notes/release_26_11.rst
+++ b/doc/guides/rel_notes/release_26_11.rst
@@ -226,6 +226,9 @@ Removed Items
The only remaining method for detecting LLDP packets is by using
the mbuf packet type in conjunction with the ``enable_lldp`` devarg.
+* sched: Removed the private random number generator used by RED: the
+ inline function ``rte_fast_rand()``.
+
API Changes
-----------
diff --git a/lib/sched/rte_red.c b/lib/sched/rte_red.c
index d7534d0bee..6d20afa9dc 100644
--- a/lib/sched/rte_red.c
+++ b/lib/sched/rte_red.c
@@ -5,14 +5,9 @@
#include <math.h>
#include <eal_export.h>
#include "rte_red.h"
-#include <rte_random.h>
#include <rte_common.h>
-static int rte_red_init_done = 0; /**< Flag to indicate that global
initialisation is done */
-RTE_EXPORT_SYMBOL(rte_red_rand_val)
-uint32_t rte_red_rand_val = 0; /**< Random value cache */
-RTE_EXPORT_SYMBOL(rte_red_rand_seed)
-uint32_t rte_red_rand_seed = 0; /**< Seed for random number generation */
+static int rte_red_init_done; /**< Flag to indicate that global
initialisation is done */
/**
* table[i] = log2(1-Wq) * Scale * -1
@@ -116,8 +111,6 @@ rte_red_config_init(struct rte_red_config *red_cfg,
* Initialize the RED module if not already done
*/
if (!rte_red_init_done) {
- rte_red_rand_seed = rte_rand();
- rte_red_rand_val = rte_fast_rand();
__rte_red_init_tables();
rte_red_init_done = 1;
}
diff --git a/lib/sched/rte_red.h b/lib/sched/rte_red.h
index 3b90cc46a9..ad11941ed5 100644
--- a/lib/sched/rte_red.h
+++ b/lib/sched/rte_red.h
@@ -15,6 +15,7 @@
#include <rte_debug.h>
#include <rte_cycles.h>
#include <rte_branch_prediction.h>
+#include <rte_random.h>
#ifdef __cplusplus
extern "C" {
@@ -34,8 +35,6 @@ extern "C" {
/**
* Externs
*/
-extern uint32_t rte_red_rand_val;
-extern uint32_t rte_red_rand_seed;
extern uint16_t rte_red_log2_1_minus_Wq[RTE_RED_WQ_LOG2_NUM];
extern uint16_t rte_red_pow2_frac_inv[16];
@@ -102,23 +101,6 @@ rte_red_config_init(struct rte_red_config *red_cfg,
const uint16_t max_th,
const uint16_t maxp_inv);
-/**
- * @brief Generate random number for RED
- *
- * Implementation based on:
- *
http://software.intel.com/en-us/articles/fast-random-number-generator-on-the-intel-pentiumr-4-processor/
- *
- * 10 bit shift has been found through empirical tests (was 16).
- *
- * @return Random number between 0 and (2^22 - 1)
- */
-static inline uint32_t
-rte_fast_rand(void)
-{
- rte_red_rand_seed = (214013 * rte_red_rand_seed) + 2531011;
- return rte_red_rand_seed >> 10;
-}
-
/**
* @brief calculate factor to scale average queue size when queue
* becomes empty
@@ -293,12 +275,8 @@ __rte_red_drop(const struct rte_red_config *red_cfg,
struct rte_red *red)
pa_den = red_cfg->pa_const - pa_num_count;
- /* If drop, generate and save random number to be used next time */
- if (unlikely((rte_red_rand_val % pa_den) < pa_num)) {
- rte_red_rand_val = rte_fast_rand();
-
+ if (unlikely((rte_rand() % pa_den) < pa_num))
return 1;
- }
/* No drop */
return 0;
--
2.53.0
