On 05/18/2015 05:35 PM, Zoltan Kiss wrote:
> 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>
Acked-by: Olivier Matz <olivier.matz at 6wind.com>
> ---
> 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
>
