On Tue, May 31, 2016 at 11:05:30PM +0200, Olivier MATZ wrote:
> Hi Jerin,
Hi Olivier,
>
> >>> /* 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;
> >>>
> >>>
> >>
> >> I also checked in the get_bulk() function, which looks like that:
> >>
> >> /* Now fill in the response ... */
> >> for (index = 0, len = cache->len - 1;
> >> index < n;
> >> ++index, len--, obj_table++)
> >> *obj_table = cache_objs[len];
> >>
> >> I think we could replace it by something like:
> >>
> >> rte_memcpy(obj_table, &cache_objs[len - n], sizeof(void *) * n);
> >>
> >> The only difference is that it won't reverse the pointers in the
> >> table, but I don't see any problem with that.
> >>
> >> What do you think?
> >
> > In true sense, it will _not_ be LIFO. Not sure about cache usage
> > implications
> > on the specific use cases.
>
> Today, the objects pointers are reversed only in the get(). It means
> that this code:
>
> rte_mempool_get_bulk(mp, table, 4);
> for (i = 0; i < 4; i++)
> printf("obj = %p\n", t[i]);
> rte_mempool_put_bulk(mp, table, 4);
>
>
> printf("-----\n");
> rte_mempool_get_bulk(mp, table, 4);
> for (i = 0; i < 4; i++)
> printf("obj = %p\n", t[i]);
> rte_mempool_put_bulk(mp, table, 4);
>
> prints:
>
> addr1
> addr2
> addr3
> addr4
> -----
> addr4
> addr3
> addr2
> addr1
>
> Which is quite strange.
IMO, It is the expected LIFO behavior. Right ?
What is not expected is the following, which is the case after change. Or Am I
missing something here?
addr1
addr2
addr3
addr4
-----
addr1
addr2
addr3
addr4
>
> I don't think it would be an issue to replace the loop by a
> rte_memcpy(), it may increase the copy speed and it will be
> more coherent with the put().
>
>
> Olivier
