Re: [dpdk-dev] [PATCH v5 1/1] mbuf: add bulk free function

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

> Add function for freeing a bulk of mbufs.
> 
> v5:
> * Rename variables from "free" to "pending" for improved readability.
> * Add prefix __ to rte_pktmbuf_free_seg_via_array().
> * Add array size parameter to __rte_pktmbuf_free_seg_via_array().
>   The compiler will optimize the parameter away anyway.
> * Add description to __rte_pktmbuf_free_seg_via_array().
> * Minor description updates.
> v4:
> * Mark as experimental by adding __rte_experimental.
> * Add function to experimental section of map file.
> * Fix source code formatting regarding pointer to pointer.
> * Squash multiple modifications into one.
> v3:
> * Bugfix: Handle pakets with multiple segments.
> * Add inline helper function, mainly for readability.
> * Fix source code formatting regarding indentation.
> v2:
> * Function is not inline.
> * Optimize to free multible mbufs belonging to the same mempool in
>   bulk. Inspired by ixgbe_tx_free_bufs(), but allowing NULL pointers
>   in the array, just like rte_pktmbuf_free() can take a NULL pointer.
> * Use unsigned int instead of unsigned. Passes checkpatch, but
>   mismatches the original coding style of the modified files.
> * Fix a typo in the description headline: mempools is plural.
> 
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> ---
>  lib/librte_mbuf/rte_mbuf.c           | 66 ++++++++++++++++++++++++++++
>  lib/librte_mbuf/rte_mbuf.h           | 15 +++++++
>  lib/librte_mbuf/rte_mbuf_version.map |  1 +
>  3 files changed, 82 insertions(+)
> 
> diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
> index 37718d49c..de5659baa 100644
> --- a/lib/librte_mbuf/rte_mbuf.c
> +++ b/lib/librte_mbuf/rte_mbuf.c
> @@ -245,6 +245,72 @@ int rte_mbuf_check(const struct rte_mbuf *m, int is_header,
>  	return 0;
>  }
> 
> +/**
> + * @internal helper function for freeing a bulk of packet mbuf segments
> + * via an array holding the packet mbuf segments from the same mempool
> + * pending to be freed.
> + *
> + * @param m
> + *  The packet mbuf segment to be freed.
> + * @param pending
> + *  Pointer to the array of packet mbuf segments pending to be freed.
> + * @param nb_pending
> + *  Pointer to the number of elements held in the array.
> + * @param pending_sz
> + *  Number of elements the array can hold.
> + *  Note: The compiler should optimize this parameter away when using a
> + *  constant value, such as RTE_PKTMBUF_FREE_PENDING_SZ.
> + */
> +static __rte_always_inline void
> +__rte_pktmbuf_free_seg_via_array(struct rte_mbuf *m,
> +	struct rte_mbuf ** const pending, unsigned int * const nb_pending,
> +	const unsigned int pending_sz)
> +{
> +	m = rte_pktmbuf_prefree_seg(m);
> +	if (likely(m != NULL)) {
> +		if (*nb_pending == pending_sz ||
> +		    (*nb_pending > 0 && m->pool != pending[0]->pool)) {
> +			rte_mempool_put_bulk(pending[0]->pool,
> +					(void **)pending, *nb_pending);
> +			*nb_pending = 0;
> +		}
> +
> +		pending[(*nb_pending)++] = m;
> +	}
> +}
> +
> +/**
> + * Size of the array holding mbufs from the same membool pending to be freed
> + * in bulk.
> + */
> +#define RTE_PKTMBUF_FREE_PENDING_SZ 64
> +
> +/* Free a bulk of packet mbufs back into their original mempools. */
> +void rte_pktmbuf_free_bulk(struct rte_mbuf **mbufs, unsigned int count)
> +{
> +	struct rte_mbuf *m, *m_next, *pending[RTE_PKTMBUF_FREE_PENDING_SZ];
> +	unsigned int idx, nb_pending = 0;
> +
> +	for (idx = 0; idx < count; idx++) {
> +		m = mbufs[idx];
> +		if (unlikely(m == NULL))
> +			continue;
> +
> +		__rte_mbuf_sanity_check(m, 1);
> +
> +		do {
> +			m_next = m->next;
> +			__rte_pktmbuf_free_seg_via_array(m,
> +					pending, &nb_pending,
> +					RTE_PKTMBUF_FREE_PENDING_SZ);
> +			m = m_next;
> +		} while (m != NULL);
> +	}
> +
> +	if (nb_pending > 0)
> +		rte_mempool_put_bulk(pending[0]->pool, (void **)pending, nb_pending);
> +}
> +
>  /* dump a mbuf on console */
>  void
>  rte_pktmbuf_dump(FILE *f, const struct rte_mbuf *m, unsigned dump_len)
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index 98225ec80..a02c8b12c 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -1907,6 +1907,21 @@ static inline void rte_pktmbuf_free(struct rte_mbuf *m)
>  	}
>  }
> 
> +/**
> + * Free a bulk of packet mbufs back into their original mempools.
> + *
> + * Free a bulk of mbufs, and all their segments in case of chained buffers.
> + * Each segment is added back into its original mempool.
> + *
> + *  @param mbufs
> + *    Array of pointers to packet mbufs.
> + *    The array may contain NULL pointers.
> + *  @param count
> + *    Array size.
> + */
> +__rte_experimental
> +void rte_pktmbuf_free_bulk(struct rte_mbuf **mbufs, unsigned int count);
> +
>  /**
>   * Creates a "clone" of the given packet mbuf.
>   *
> diff --git a/lib/librte_mbuf/rte_mbuf_version.map b/lib/librte_mbuf/rte_mbuf_version.map
> index 2662a37bf..cd6154ef2 100644
> --- a/lib/librte_mbuf/rte_mbuf_version.map
> +++ b/lib/librte_mbuf/rte_mbuf_version.map
> @@ -50,4 +50,5 @@ EXPERIMENTAL {
>  	global:
> 
>  	rte_mbuf_check;
> +	rte_pktmbuf_free_bulk;
>  } DPDK_18.08;
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 2.17.1