Re: [dpdk-dev] [PATCH v2] rte_mbuf: mbuf bulk alloc/free functions added + unittest

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Vadim,

> -----Original Message-----
> From: vadim.suraev@gmail.com [mailto:vadim.suraev@gmail.com]
> Sent: Tuesday, March 17, 2015 9:36 PM
> To: dev@dpdk.org
> Cc: olivier.matz@6wind.com; stephen@networkplumber.org; Ananyev, Konstantin; vadim.suraev@gmail.com
> Subject: [PATCH v2] rte_mbuf: mbuf bulk alloc/free functions added + unittest
> 
> From: "vadim.suraev@gmail.com" <vadim.suraev@gmail.com>
> 
> This patch adds mbuf bulk allocation/freeing functions and unittest
> 
> Signed-off-by: Vadim Suraev
> <vadim.suraev@gmail.com>
> ---
> New in v2:
>     - function rte_pktmbuf_alloc_bulk added
>     - function rte_pktmbuf_bulk_free added
>     - function rte_pktmbuf_free_chain added
>     - applied reviewers' comments
> 
>  app/test/test_mbuf.c       |   94 +++++++++++++++++++++++++++++++++++++++++++-
>  lib/librte_mbuf/rte_mbuf.h |   89 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 182 insertions(+), 1 deletion(-)
> 
> diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c
> index 1ff66cb..b20c6a4 100644
> --- a/app/test/test_mbuf.c
> +++ b/app/test/test_mbuf.c
> @@ -77,6 +77,7 @@
>  #define REFCNT_RING_SIZE        (REFCNT_MBUF_NUM * REFCNT_MAX_REF)
> 
>  #define MAKE_STRING(x)          # x
> +#define MBUF_POOL_LOCAL_CACHE_SIZE 32
> 
>  static struct rte_mempool *pktmbuf_pool = NULL;
> 
> @@ -405,6 +406,84 @@ test_pktmbuf_pool(void)
>  	return ret;
>  }
> 
> +/* test pktmbuf bulk allocation and freeing
> +*/
> +static int
> +test_pktmbuf_pool_bulk(void)
> +{
> +	unsigned i;
> +	/* size of mempool - size of local cache, otherwise may fail */
> +	unsigned mbufs_to_allocate = NB_MBUF - MBUF_POOL_LOCAL_CACHE_SIZE;
> +	struct rte_mbuf *m[mbufs_to_allocate];
> +	int ret = 0;
> +	unsigned mbuf_count_before_allocation = rte_mempool_count(pktmbuf_pool);
> +
> +	for (i = 0; i < mbufs_to_allocate; i++)
> +		m[i] = NULL;
> +	/* alloc NB_MBUF-MBUF_POOL_LOCAL_CACHE_SIZE mbufs */
> +	ret = rte_pktmbuf_alloc_bulk(pktmbuf_pool, m, mbufs_to_allocate);
> +	if (ret) {
> +		printf("cannot allocate %d mbufs bulk mempool_cnt=%d ret=%d\n",
> +			mbufs_to_allocate,
> +			rte_mempool_count(pktmbuf_pool),
> +			ret);
> +		return -1;
> +	}
> +	if ((rte_mempool_count(pktmbuf_pool) + mbufs_to_allocate) !=
> +	    mbuf_count_before_allocation) {
> +		printf("mempool count %d + allocated %d != initial %d\n",
> +			rte_mempool_count(pktmbuf_pool),
> +			mbufs_to_allocate,
> +			mbuf_count_before_allocation);
> +		return -1;
> +	}
> +	/* free them */
> +	rte_pktmbuf_bulk_free(m, mbufs_to_allocate);
> +
> +	if (rte_mempool_count(pktmbuf_pool)  != mbuf_count_before_allocation) {
> +		printf("mempool count %d != initial %d\n",
> +			rte_mempool_count(pktmbuf_pool),
> +			mbuf_count_before_allocation);
> +		return -1;
> +	}
> +	for (i = 0; i < mbufs_to_allocate; i++)
> +		m[i] = NULL;
> +
> +	/* alloc NB_MBUF-MBUF_POOL_LOCAL_CACHE_SIZE mbufs */
> +	ret = rte_pktmbuf_alloc_bulk(pktmbuf_pool, m, mbufs_to_allocate);
> +	if (ret) {
> +		printf("cannot allocate %d mbufs bulk mempool_cnt=%d ret=%d\n",
> +			mbufs_to_allocate,
> +			rte_mempool_count(pktmbuf_pool),
> +			ret);
> +		return -1;
> +	}
> +	if ((rte_mempool_count(pktmbuf_pool) + mbufs_to_allocate) !=
> +	    mbuf_count_before_allocation) {
> +		printf("mempool count %d + allocated %d != initial %d\n",
> +			rte_mempool_count(pktmbuf_pool),
> +					  mbufs_to_allocate,
> +					  mbuf_count_before_allocation);
> +		return -1;
> +	}
> +
> +	/* chain it */
> +	for (i = 0; i < mbufs_to_allocate - 1; i++) {
> +		m[i]->next = m[i + 1];
> +		m[0]->nb_segs++;
> +	}
> +	/* free them */
> +	rte_pktmbuf_free_chain(m[0]);
> +
> +	if (rte_mempool_count(pktmbuf_pool)  != mbuf_count_before_allocation) {
> +		printf("mempool count %d != initial %d\n",
> +			rte_mempool_count(pktmbuf_pool),
> +					  mbuf_count_before_allocation);
> +		return -1;
> +	}
> +	return ret;
> +}
> +
>  /*
>   * test that the pointer to the data on a packet mbuf is set properly
>   */
> @@ -766,7 +845,8 @@ test_mbuf(void)
>  	if (pktmbuf_pool == NULL) {
>  		pktmbuf_pool =
>  			rte_mempool_create("test_pktmbuf_pool", NB_MBUF,
> -					   MBUF_SIZE, 32,
> +					   MBUF_SIZE,
> +					   MBUF_POOL_LOCAL_CACHE_SIZE,
>  					   sizeof(struct rte_pktmbuf_pool_private),
>  					   rte_pktmbuf_pool_init, NULL,
>  					   rte_pktmbuf_init, NULL,
> @@ -790,6 +870,18 @@ test_mbuf(void)
>  		return -1;
>  	}
> 
> +	/* test bulk allocation and freeing */
> +	if (test_pktmbuf_pool_bulk() < 0) {
> +		printf("test_pktmbuf_pool_bulk() failed\n");
> +		return -1;
> +	}
> +
> +	/* once again to ensure all mbufs were freed */
> +	if (test_pktmbuf_pool_bulk() < 0) {
> +		printf("test_pktmbuf_pool_bulk() failed\n");
> +		return -1;
> +	}
> +
>  	/* test that the pointer to the data on a packet mbuf is set properly */
>  	if (test_pktmbuf_pool_ptr() < 0) {
>  		printf("test_pktmbuf_pool_ptr() failed\n");
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index 17ba791..995237d 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -825,6 +825,95 @@ static inline void rte_pktmbuf_free(struct rte_mbuf *m)
>  }
> 
>  /**
> + * Allocate a bulk of mbufs, initiate refcnt and resets
> + *
> + * @param pool
> + *    memory pool to allocate from
> + * @param mbufs
> + *    Array of pointers to mbuf
> + * @param count
> + *    Array size
> + */
> +static inline int rte_pktmbuf_alloc_bulk(struct rte_mempool *pool,
> +					 struct rte_mbuf **mbufs,
> +					 unsigned count)
> +{
> +	unsigned idx;
> +	int rc = 0;
> +
> +	rc = rte_mempool_get_bulk(pool, (void **)mbufs, count);
> +	if (unlikely(rc))
> +		return rc;
> +
> +	for (idx = 0; idx < count; idx++) {
> +		RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> +		rte_mbuf_refcnt_set(mbufs[idx], 1);
> +		rte_pktmbuf_reset(mbufs[idx]);
> +	}
> +	return rc;
> +}
> +
> +/**
> + * Free a bulk of mbufs into its original mempool.
> + * This function assumes refcnt equals 1
> + * as well as the freed mbufs are direct

I think your forgot to mention in comments one more requirement for that function:
all mbufs have to be from the same mempool.

> + *
> + * @param mbufs
> + *    Array of pointers to mbuf
> + * @param count
> + *    Array size
> + */
> +static inline void rte_pktmbuf_bulk_free(struct rte_mbuf **mbufs,
> +					 unsigned count)
> +{
> +	unsigned idx;
> +
> +	RTE_MBUF_ASSERT(count > 0);
> +
> +	for (idx = 0; idx < count; idx++) {
> +		rte_mbuf_refcnt_update(mbufs[idx], -1);

You can do just:
rte_mbuf_refcnt_set(m, 0);
here and move your assert above it.
Something like:
RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 1);
rte_mbuf_refcnt_set(m, 0);

Also probably would be a good thing to add one more assert here,
something like:
RTE_MBUF_ASSERT(mbufs[idx]->pool == mufs[0]->pool);

> +		RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(mbufs[idx]) == 0);
> +	}
> +	rte_mempool_put_bulk(mbufs[0]->pool, (void **)mbufs, count);
> +}
> +
> +/**
> + * Free chained (scattered) mbufs into its original mempool(s).
> + *
> + * @param head
> + *    The head of mbufs to be freed chain. Must not be NULL
> + */
> +static inline void rte_pktmbuf_free_chain(struct rte_mbuf *head)
> +{
> +	struct rte_mbuf *mbufs[head->nb_segs];
> +	unsigned mbufs_count = 0;
> +	struct rte_mbuf *next;
> +
> +	while (head) {
> +		next = head->next;
> +		head->next = NULL;

Shouldn't the line above be inside if (head != NULL) {...} block?

> +		head = __rte_pktmbuf_prefree_seg(head);
> +		if (likely(head != NULL)) {
> +			RTE_MBUF_ASSERT(rte_mbuf_refcnt_read(head) == 0);

I don't think there is any use of the assert above.
If prefree_seg returns non-NULL value, it sets refcnt to 0 for that mbuf.

> +			if (likely((!mbufs_count) ||
> +				   (head->pool == mbufs[0]->pool)))
> +				mbufs[mbufs_count++] = head;
> +			else {
> +				rte_mempool_put_bulk(mbufs[0]->pool,
> +						     (void **)mbufs,
> +						     mbufs_count);
> +				mbufs_count = 0;
> +			}
> +		}
> +		head = next;
> +	}
> +	if (mbufs_count > 0)
> +		rte_mempool_put_bulk(mbufs[0]->pool,
> +				     (void **)mbufs,
> +				     mbufs_count);
> +}
> +
> +/**
>   * Creates a "clone" of the given packet mbuf.
>   *
>   * Walks through all segments of the given packet mbuf, and for each of them:
> --
> 1.7.9.5