[dpdk-dev] [PATCH] mbuf: replace c memcpy code semantics with optimized rte_memcpy
Jerin Jacob
jerin.jacob at caviumnetworks.com
Tue May 24 17:17:01 CEST 2016
On Tue, May 24, 2016 at 04:59:47PM +0200, Olivier Matz wrote:
> Hi Jerin,
>
>
> On 05/24/2016 04:50 PM, Jerin Jacob wrote:
> > Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
> > ---
> > lib/librte_mempool/rte_mempool.h | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> > index ed2c110..ebe399a 100644
> > --- a/lib/librte_mempool/rte_mempool.h
> > +++ b/lib/librte_mempool/rte_mempool.h
> > @@ -74,6 +74,7 @@
> > #include <rte_memory.h>
> > #include <rte_branch_prediction.h>
> > #include <rte_ring.h>
> > +#include <rte_memcpy.h>
> >
> > #ifdef __cplusplus
> > extern "C" {
> > @@ -917,7 +918,6 @@ __mempool_put_bulk(struct rte_mempool *mp, void * const *obj_table,
> > unsigned n, __rte_unused int is_mp)
> > {
> > struct rte_mempool_cache *cache;
> > - uint32_t index;
> > void **cache_objs;
> > unsigned lcore_id = rte_lcore_id();
> > uint32_t cache_size = mp->cache_size;
> > @@ -946,8 +946,7 @@ __mempool_put_bulk(struct rte_mempool *mp, void * const *obj_table,
> > */
> >
> > /* Add elements back into the cache */
> > - for (index = 0; index < n; ++index, obj_table++)
> > - cache_objs[index] = *obj_table;
> > + rte_memcpy(&cache_objs[0], obj_table, sizeof(void *) * n);
> >
> > cache->len += n;
> >
> >
>
> The commit title should be "mempool" instead of "mbuf".
I will fix it.
> Are you seeing some performance improvement by using rte_memcpy()?
Yes, In some case, In default case, It was replaced with memcpy by the
compiler itself(gcc 5.3). But when I tried external mempool manager patch and
then performance dropped almost 800Kpps. Debugging further it turns out that
external mempool managers unrelated change was knocking out the memcpy.
explicit rte_memcpy brought back 500Kpps. Remaing 300Kpps drop is still
unknown(In my test setup, packets are in the local cache, so it must be
something do with __mempool_put_bulk text alignment change or similar.
Anyone else observed performance drop with external poolmanager?
Jerin
>
> Regards
> Olivier
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