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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>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
This commit is contained in:
Zoltan Kiss 2015-05-18 16:35:14 +01:00 committed by Thomas Monjalon
parent b96250c089
commit 462321b44a
2 changed files with 6 additions and 4 deletions
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8
lib/librte_mempool/rte_mempool.c
View File

@ -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. */

2
lib/librte_mempool/rte_mempool.h
View File

@ -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