Re: [dpdk-dev] [PATCH v2 1/2] eal/mempool: introduce check for external mempool availability

[Hemant Agrawal <hemant.agrawal@nxp.com>]

HI David,

> -----Original Message-----
> From: Hunt, David [mailto:david.hunt@intel.com]
> Sent: Friday, September 16, 2016 2:44 PM
> To: Hemant Agrawal <hemant.agrawal@nxp.com>; olivier.matz@6wind.com
> Cc: dev@dpdk.org; jerin.jacob@caviumnetworks.com
> Subject: Re: [PATCH v2 1/2] eal/mempool: introduce check for external
> mempool availability
> 
> Hi Hemant,
> 
> On 15/9/2016 6:13 PM, Hemant Agrawal wrote:
> > External offloaded mempool may not be available always. This check
> > enables run time verification of the presence of external mempool
> > before the mempool ops are installed.
> >
> > An application built with a specific external mempool may work fine on
> > host. But, may not work on VM, specificaly if non-hw specific
> > interfaces are used e.g. virtio-net.
> >
> > This is required to make sure that same application can work in all
> > environment for a given hw platform.
> >
> > The solution proposed here is that rte_mempool_set_ops_byname should
> > return specific error in case the current execution environment is not
> > supporting the given mempool. Thereby allowing it to fallback on
> > software mempool implementation e.g. "ring_mp_mc"
> >
> > This patch introduces new optional "pool_verify" as mempool ops
> > function to check if external mempool instance is available or not.
> 
> I've a small suggestion around the naming of the new functions. It seems to me
> that this patch is more about mempool handler 'support' than 'verification'.
> Could I suggest a different name for this new function? I think maybe
> "supported" may be more appropriate than "pool_verify". The return code that's
> returned when a mempool handler is not available is -EOPNOTSUPP, which is
> what suggested the word "supported" to me. I think that:
> 
> 	if (ops->supported)
> 		return ops->supported(mp);
> 
> makes for slightly easier reading. The wrapper function would logically then be
> called  rte_mempool_ops_supported().

[Hemant] Good suggestion. I will update it in next version. 

> 
> 
> > Signed-off-by: Hemant Agrawal <hemant.agrawal@nxp.com>
> > ---
> > Changes in v2:
> > * fixed the pool_verify copy in rte_mempool_register_ops
> > ---
> >   lib/librte_mempool/rte_mempool.h       | 21 +++++++++++++++++++++
> >   lib/librte_mempool/rte_mempool_ops.c   | 19 +++++++++++++++++++
> >   lib/librte_mempool/rte_mempool_ring.c  |  4 ++++
> >   lib/librte_mempool/rte_mempool_stack.c |  3 ++-
> >   4 files changed, 46 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/librte_mempool/rte_mempool.h
> b/lib/librte_mempool/rte_mempool.h
> > index 0243f9e..8599df1 100644
> > --- a/lib/librte_mempool/rte_mempool.h
> > +++ b/lib/librte_mempool/rte_mempool.h
> > @@ -387,6 +387,12 @@ typedef int (*rte_mempool_dequeue_t)(struct
> rte_mempool *mp,
> >    */
> >   typedef unsigned (*rte_mempool_get_count)(const struct rte_mempool
> *mp);
> >
> > +/**
> > + * Return if the given external mempool is available for this instance.
> > + * it is optional to implement for mempools
> > + */
> > +typedef int (*rte_mempool_pool_verify)(const struct rte_mempool *mp);
> > +
> >   /** Structure defining mempool operations structure */
> >   struct rte_mempool_ops {
> >   	char name[RTE_MEMPOOL_OPS_NAMESIZE]; /**< Name of mempool
> ops struct. */
> > @@ -395,6 +401,8 @@ struct rte_mempool_ops {
> >   	rte_mempool_enqueue_t enqueue;   /**< Enqueue an object. */
> >   	rte_mempool_dequeue_t dequeue;   /**< Dequeue an object. */
> >   	rte_mempool_get_count get_count; /**< Get qty of available objs. */
> > +	rte_mempool_pool_verify pool_verify;
> > +	/**< Verify if external mempool is available for usages*/
> >   } __rte_cache_aligned;
> >
> >   #define RTE_MEMPOOL_MAX_OPS_IDX 16  /**< Max registered ops structs
> */
> > @@ -516,6 +524,18 @@ void
> >   rte_mempool_ops_free(struct rte_mempool *mp);
> >
> >   /**
> > + * @internal wrapper to verify the external mempool availability
> > + *
> > + * @param mp
> > + *   Pointer to the memory pool.
> > + * @return
> > + *   0: Success; external mempool instance is available
> > + * - <0: Error; external mempool instance is not available
> > + */
> > +int
> > +rte_mempool_ops_pool_verify(const struct rte_mempool *mp);
> > +
> > +/**
> >    * Set the ops of a mempool.
> >    *
> >    * This can only be done on a mempool that is not populated, i.e. just after
> > @@ -531,6 +551,7 @@ rte_mempool_ops_free(struct rte_mempool *mp);
> >    *   - 0: Success; the mempool is now using the requested ops functions.
> >    *   - -EINVAL - Invalid ops struct name provided.
> >    *   - -EEXIST - mempool already has an ops struct assigned.
> > + *   - -EOPNOTSUPP  - mempool instance not available.
> >    */
> >   int
> >   rte_mempool_set_ops_byname(struct rte_mempool *mp, const char *name,
> > diff --git a/lib/librte_mempool/rte_mempool_ops.c
> b/lib/librte_mempool/rte_mempool_ops.c
> > index 5f24de2..c2e765f 100644
> > --- a/lib/librte_mempool/rte_mempool_ops.c
> > +++ b/lib/librte_mempool/rte_mempool_ops.c
> > @@ -85,6 +85,7 @@ rte_mempool_register_ops(const struct
> rte_mempool_ops *h)
> >   	ops->enqueue = h->enqueue;
> >   	ops->dequeue = h->dequeue;
> >   	ops->get_count = h->get_count;
> > +	ops->pool_verify = h->pool_verify;
> >
> >   	rte_spinlock_unlock(&rte_mempool_ops_table.sl);
> >
> > @@ -123,6 +124,18 @@ rte_mempool_ops_get_count(const struct
> rte_mempool *mp)
> >   	return ops->get_count(mp);
> >   }
> >
> > +/* wrapper to check if given external mempool is available for this
> instance.*/
> > +int
> > +rte_mempool_ops_pool_verify(const struct rte_mempool *mp)
> > +{
> > +	struct rte_mempool_ops *ops;
> > +
> > +	ops = rte_mempool_get_ops(mp->ops_index);
> > +	if (ops->pool_verify)
> > +		return ops->pool_verify(mp);
> > +	return 0;
> > +}
> > +
> >   /* sets mempool ops previously registered by rte_mempool_register_ops. */
> >   int
> >   rte_mempool_set_ops_byname(struct rte_mempool *mp, const char *name,
> > @@ -146,6 +159,12 @@ rte_mempool_set_ops_byname(struct rte_mempool
> *mp, const char *name,
> >   	if (ops == NULL)
> >   		return -EINVAL;
> >
> > +	/*verify if the given mempool is available for this instance */
> > +	if (ops->pool_verify) {
> > +		if (ops->pool_verify(mp))
> > +			return -EOPNOTSUPP;
> > +	}
> > +
> >   	mp->ops_index = i;
> >   	mp->pool_config = pool_config;
> >   	return 0;
> > diff --git a/lib/librte_mempool/rte_mempool_ring.c
> b/lib/librte_mempool/rte_mempool_ring.c
> > index b9aa64d..d86d5e0 100644
> > --- a/lib/librte_mempool/rte_mempool_ring.c
> > +++ b/lib/librte_mempool/rte_mempool_ring.c
> > @@ -126,6 +126,7 @@ static const struct rte_mempool_ops ops_mp_mc = {
> >   	.enqueue = common_ring_mp_enqueue,
> >   	.dequeue = common_ring_mc_dequeue,
> >   	.get_count = common_ring_get_count,
> > +	.pool_verify = NULL,
> >   };
> >
> >   static const struct rte_mempool_ops ops_sp_sc = {
> > @@ -135,6 +136,7 @@ static const struct rte_mempool_ops ops_sp_sc = {
> >   	.enqueue = common_ring_sp_enqueue,
> >   	.dequeue = common_ring_sc_dequeue,
> >   	.get_count = common_ring_get_count,
> > +	.pool_verify = NULL,
> >   };
> >
> >   static const struct rte_mempool_ops ops_mp_sc = {
> > @@ -144,6 +146,7 @@ static const struct rte_mempool_ops ops_mp_sc = {
> >   	.enqueue = common_ring_mp_enqueue,
> >   	.dequeue = common_ring_sc_dequeue,
> >   	.get_count = common_ring_get_count,
> > +	.pool_verify = NULL,
> >   };
> >
> >   static const struct rte_mempool_ops ops_sp_mc = {
> > @@ -153,6 +156,7 @@ static const struct rte_mempool_ops ops_sp_mc = {
> >   	.enqueue = common_ring_sp_enqueue,
> >   	.dequeue = common_ring_mc_dequeue,
> >   	.get_count = common_ring_get_count,
> > +	.pool_verify = NULL,
> >   };
> >
> >   MEMPOOL_REGISTER_OPS(ops_mp_mc);
> > diff --git a/lib/librte_mempool/rte_mempool_stack.c
> b/lib/librte_mempool/rte_mempool_stack.c
> > index 5fd8af2..0198b70 100644
> > --- a/lib/librte_mempool/rte_mempool_stack.c
> > +++ b/lib/librte_mempool/rte_mempool_stack.c
> > @@ -141,7 +141,8 @@ static struct rte_mempool_ops ops_stack = {
> >   	.free = stack_free,
> >   	.enqueue = stack_enqueue,
> >   	.dequeue = stack_dequeue,
> > -	.get_count = stack_get_count
> > +	.get_count = stack_get_count,
> > +	.pool_verify = NULL,
> >   };
> >
> >   MEMPOOL_REGISTER_OPS(ops_stack);
> 
> Regards,
> Dave.