Re: [dpdk-dev] [PATCH] mempool: Reduce rte_mempool structure size

["Wiles, Keith" <keith.wiles@intel.com>]

>Hi Keith,
>
>Looks good, thanks. Please find some comments below.
>
>> [PATCH] mempool: Reduce rte_mempool structure size
>
>nit: we usually avoid uppercase letters in title

Will make that change for v2. Why no uppercase letters in the title, seems a bit odd to me in this case??
>
>On 02/03/2016 12:02 AM, Keith Wiles wrote:
>> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
>> index aff5f6d..bdf8e2e 100644
>> --- a/lib/librte_mempool/rte_mempool.c
>> +++ b/lib/librte_mempool/rte_mempool.c
>> @@ -450,15 +450,11 @@ rte_mempool_xmem_create(const char *name, unsigned n, unsigned elt_size,
>>  	int page_size = getpagesize();
>>  
>>  	/* compilation-time checks */
>> +#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
>>  	RTE_BUILD_BUG_ON((sizeof(struct rte_mempool) &
>>  			  RTE_CACHE_LINE_MASK) != 0);
>> -#if RTE_MEMPOOL_CACHE_MAX_SIZE > 0
>>  	RTE_BUILD_BUG_ON((sizeof(struct rte_mempool_cache) &
>>  			  RTE_CACHE_LINE_MASK) != 0);
>> -	RTE_BUILD_BUG_ON((offsetof(struct rte_mempool, local_cache) &
>> -			  RTE_CACHE_LINE_MASK) != 0);
>> -#endif
>> -#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
>
>I don't think the #ifdef RTE_LIBRTE_MEMPOOL_DEBUG should be moved.
>It should only protects the checks on stats which are enabled
>in debug mode.

Will make that change for v2.
>
>> @@ -194,10 +192,7 @@ struct rte_mempool {
>>  
>>  	unsigned private_data_size;      /**< Size of private data. */
>>  
>> -#if RTE_MEMPOOL_CACHE_MAX_SIZE > 0
>> -	/** Per-lcore local cache. */
>> -	struct rte_mempool_cache local_cache[RTE_MAX_LCORE];
>> -#endif
>> +	struct rte_mempool_cache *local_cache; /**< Per-lcore local cache */
>>  
>>  #ifdef RTE_LIBRTE_MEMPOOL_DEBUG
>>  	/** Per-lcore statistics. */
>
>As you noticed it in your initial mail, this changes the ABI. I
>think your patch justifies the ABI change, so I think it should
>follow the ABI change process described in
>dpdk/doc/guides/contributing/versioning.rst.
>
>From what I understand of versioning.rst, these kind of changes
>requires a deprecation notice first, and will be integrated in
>next version. I don't think it's easy to keep a backward compat
>in this case, especially because the rte_mempool structure is
>used by several inlined functions.

I am reading the API doc and need to understand this process a bit more, but from what I can tell I need to add a ifdef RTE_NEXT_ABI around the new structure and old. Not sure where else I need to do that as compat is a bit hard as you stated. The API revision file is there something that needs to be done in that vile too?

You can reply to me directly it you like to save some bandwidth.
>
>Regards,
>Olivier
>


Regards,
Keith