[dpdk-dev] [PATCH] Function __mempool_get_bulk() returns wrong count.

[Ananyev, Konstantin]

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Wiles, Roger Keith
> Sent: Saturday, September 27, 2014 7:42 PM
> To: <dev at dpdk.org>
> Subject: [dpdk-dev] [PATCH] Function __mempool_get_bulk() returns wrong count.
> 
> 
> When __mempool_get_bulk() grabs entries from the cache it
> returns zero instead of the number of entries obtained. Plus
> the stats were increased by the wrong count of objects.
> 
> Signed-off-by: Keith Wiles <keith.wiles at windriver.com>
> ---
>  lib/librte_mempool/rte_mempool.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> index 299d4d7..6750e78 100644
> --- a/lib/librte_mempool/rte_mempool.h
> +++ b/lib/librte_mempool/rte_mempool.h
> @@ -988,9 +988,9 @@ __mempool_get_bulk(struct rte_mempool *mp, void **obj_table,
> 
>         cache->len -= n;
> 
> -       __MEMPOOL_STAT_ADD(mp, get_success, n_orig);
> +       __MEMPOOL_STAT_ADD(mp, get_success, n);

As I can see n == n_orig.
We can completely remove n_orig, but from other side - I don't see any harm here. 

> 
> -       return 0;
> +       return n;

As I can see, __mempool_get_bulk supposed to return 0,
if all n objects were allocated from mbuf, or a negative error code otherwise.
Check all usages of __mempool_get_bulk(), plus the fact that it does below:
ret = rte_ring_mc_dequeue_bulk(mp->ring, obj_table, n);
and rte_ring_mc_dequeue_bulk() is just wrapper for __rte_ring_mc_do_dequeue(..., n, RTE_RING_QUEUE_FIXED);
I.e. - either allocate all n objects, or return with failure.
So, yes we should return 0 here.
The only thing that probably needs to be done here: fix the comments.
Instead of:
- >=0: Success; number of objects supplied.
Something like:
- 0: Success; n objects supplied.

> 
>  ring_dequeue:
>  #endif /* RTE_MEMPOOL_CACHE_MAX_SIZE > 0 */
> @@ -1004,7 +1004,7 @@ ring_dequeue:
>         if (ret < 0)
>                 __MEMPOOL_STAT_ADD(mp, get_fail, n_orig);
>         else
> -               __MEMPOOL_STAT_ADD(mp, get_success, n_orig);
> +               __MEMPOOL_STAT_ADD(mp, get_success, ret);

That seems incorrect tom me.
ret would be either 0 on success, or negative error value.

Konstantin


> 
>         return ret;
>  }
> --
> 2.1.0Keith Wiles, Principal Technologist with CTO office, Wind River mobile 972-213-5533


As I can see