Re: [dpdk-dev] [PATCH] mempool: limit cache_size

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

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Zoltan Kiss
> Sent: Monday, May 18, 2015 1:28 PM
> To: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] mempool: limit cache_size
> 
> Hi,
> 
> Any opinion on this patch?
> 
> Regards,
> 
> Zoltan
> 
> On 13/05/15 19:59, Zoltan Kiss wrote:
> > Otherwise cache_flushthresh can be bigger than n, and
> > a consumer can starve others by keeping every element
> > either in use or in the cache.
> >
> > Signed-off-by: Zoltan Kiss <zoltan.kiss@linaro.org>
> > ---
> >   lib/librte_mempool/rte_mempool.c | 3 ++-
> >   lib/librte_mempool/rte_mempool.h | 2 +-
> >   2 files changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> > index cf7ed76..ca6cd9c 100644
> > --- a/lib/librte_mempool/rte_mempool.c
> > +++ b/lib/librte_mempool/rte_mempool.c
> > @@ -440,7 +440,8 @@ rte_mempool_xmem_create(const char *name, unsigned n, unsigned elt_size,
> >   	mempool_list = RTE_TAILQ_CAST(rte_mempool_tailq.head, rte_mempool_list);
> >
> >   	/* asked cache too big */
> > -	if (cache_size > RTE_MEMPOOL_CACHE_MAX_SIZE) {
> > +	if (cache_size > RTE_MEMPOOL_CACHE_MAX_SIZE ||
> > +	    (uint32_t) cache_size * CACHE_FLUSHTHRESH_MULTIPLIER > n) {
> >   		rte_errno = EINVAL;
> >   		return NULL;
> >   	}

Why just no 'cache_size > n' then?
Konstantin

> > diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> > index 9001312..a4a9610 100644
> > --- a/lib/librte_mempool/rte_mempool.h
> > +++ b/lib/librte_mempool/rte_mempool.h
> > @@ -468,7 +468,7 @@ typedef void (rte_mempool_ctor_t)(struct rte_mempool *, void *);
> >    *   If cache_size is non-zero, the rte_mempool library will try to
> >    *   limit the accesses to the common lockless pool, by maintaining a
> >    *   per-lcore object cache. This argument must be lower or equal to
> > - *   CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE. It is advised to choose
> > + *   CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE and n / 1.5. It is advised to choose
> >    *   cache_size to have "n modulo cache_size == 0": if this is
> >    *   not the case, some elements will always stay in the pool and will
> >    *   never be used. The access to the per-lcore table is of course
> >