[dpdk-dev] [PATCH] mempool: limit cache_size

[Zoltan Kiss]

Otherwise cache_flushthresh can be bigger than n, and
a consumer can starve others by keeping every element
either in use or in the cache.

Signed-off-by: Zoltan Kiss <zoltan.kiss at linaro.org>
---
 lib/librte_mempool/rte_mempool.c | 3 ++-
 lib/librte_mempool/rte_mempool.h | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index cf7ed76..ca6cd9c 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -440,7 +440,8 @@ rte_mempool_xmem_create(const char *name, unsigned n, unsigned elt_size,
 	mempool_list = RTE_TAILQ_CAST(rte_mempool_tailq.head, rte_mempool_list);
 
 	/* asked cache too big */
-	if (cache_size > RTE_MEMPOOL_CACHE_MAX_SIZE) {
+	if (cache_size > RTE_MEMPOOL_CACHE_MAX_SIZE ||
+	    (uint32_t) cache_size * CACHE_FLUSHTHRESH_MULTIPLIER > n) {
 		rte_errno = EINVAL;
 		return NULL;
 	}
diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index 9001312..a4a9610 100644
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h
@@ -468,7 +468,7 @@ typedef void (rte_mempool_ctor_t)(struct rte_mempool *, void *);
  *   If cache_size is non-zero, the rte_mempool library will try to
  *   limit the accesses to the common lockless pool, by maintaining a
  *   per-lcore object cache. This argument must be lower or equal to
- *   CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE. It is advised to choose
+ *   CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE and n / 1.5. It is advised to choose
  *   cache_size to have "n modulo cache_size == 0": if this is
  *   not the case, some elements will always stay in the pool and will
  *   never be used. The access to the per-lcore table is of course
-- 
1.9.1