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From: Zoltan Kiss <zoltan.kiss@linaro.org>
To: dev@dpdk.org
Date: Mon, 18 May 2015 16:35:14 +0100
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Subject: [dpdk-dev] [PATCH v2] mempool: limit cache_size
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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@linaro.org>
---
v2: use macro for calculation, with proper casting
lib/librte_mempool/rte_mempool.c | 8 +++++---
lib/librte_mempool/rte_mempool.h | 2 +-
2 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index cf7ed76..5cfb96b 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -68,6 +68,8 @@ static struct rte_tailq_elem rte_mempool_tailq = {
EAL_REGISTER_TAILQ(rte_mempool_tailq)
#define CACHE_FLUSHTHRESH_MULTIPLIER 1.5
+#define CALC_CACHE_FLUSHTHRESH(c) \
+ ((typeof (c))((c) * CACHE_FLUSHTHRESH_MULTIPLIER))
/*
* return the greatest common divisor between a and b (fast algorithm)
@@ -440,7 +442,8 @@ 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 ||
+ CALC_CACHE_FLUSHTHRESH(cache_size) > n) {
rte_errno = EINVAL;
return NULL;
}
@@ -565,8 +568,7 @@ rte_mempool_xmem_create(const char *name, unsigned n, unsigned elt_size,
mp->header_size = objsz.header_size;
mp->trailer_size = objsz.trailer_size;
mp->cache_size = cache_size;
- mp->cache_flushthresh = (uint32_t)
- (cache_size * CACHE_FLUSHTHRESH_MULTIPLIER);
+ mp->cache_flushthresh = CALC_CACHE_FLUSHTHRESH(cache_size);
mp->private_data_size = private_data_size;
/* calculate address of the first element for continuous mempool. */
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