[dpdk-dev] [PATCH] mempool: limit cache_size
Zoltan Kiss
zoltan.kiss at linaro.org
Mon May 18 14:50:20 CEST 2015
On 18/05/15 13:41, Ananyev, Konstantin wrote:
>
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Zoltan Kiss
>> Sent: Monday, May 18, 2015 1:28 PM
>> To: dev at dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH] mempool: limit cache_size
>>
>> Hi,
>>
>> Any opinion on this patch?
>>
>> Regards,
>>
>> Zoltan
>>
>> On 13/05/15 19:59, 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>
>>> ---
>>> 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;
>>> }
>
> Why just no 'cache_size > n' then?
The commit message says: "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."
> Konstantin
>
>>> 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
>>>
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