From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
To: Olivier MATZ <olivier.matz@6wind.com>
Cc: <dev@dpdk.org>, <thomas.monjalon@6wind.com>,
<bruce.richardson@intel.com>, <konstantin.ananyev@intel.com>
Subject: Re: [dpdk-dev] [PATCH v2] mempool: replace c memcpy code semantics with optimized rte_memcpy
Date: Wed, 1 Jun 2016 12:30:23 +0530 [thread overview]
Message-ID: <20160601070018.GA26922@localhost.localdomain> (raw)
In-Reply-To: <574DFC9A.2050304@6wind.com>
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
next prev parent reply other threads:[~2016-06-01 7:00 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-24 14:50 [dpdk-dev] [PATCH] mbuf: " Jerin Jacob
2016-05-24 14:59 ` Olivier Matz
2016-05-24 15:17 ` Jerin Jacob
2016-05-27 10:24 ` Hunt, David
2016-05-27 11:42 ` Jerin Jacob
2016-05-27 15:05 ` Thomas Monjalon
2016-05-30 8:44 ` Olivier Matz
2016-05-27 13:45 ` Hunt, David
2016-06-24 15:56 ` Hunt, David
2016-06-24 16:02 ` Olivier Matz
2016-05-26 8:07 ` [dpdk-dev] [PATCH v2] mempool: " Jerin Jacob
2016-05-30 8:45 ` Olivier Matz
2016-05-31 12:58 ` Jerin Jacob
2016-05-31 21:05 ` Olivier MATZ
2016-06-01 7:00 ` Jerin Jacob [this message]
2016-06-02 7:36 ` Olivier MATZ
2016-06-02 9:39 ` Jerin Jacob
2016-06-02 21:16 ` Olivier MATZ
2016-06-03 7:02 ` Jerin Jacob
2016-06-17 10:40 ` Olivier Matz
2016-06-24 16:04 ` Olivier Matz
2016-06-30 9:41 ` Thomas Monjalon
2016-06-30 11:38 ` Jerin Jacob
2016-06-30 12:16 ` [dpdk-dev] [PATCH v3] " Jerin Jacob
2016-06-30 17:28 ` Thomas Monjalon
2016-07-05 8:43 ` Ferruh Yigit
2016-07-05 11:32 ` Yuanhan Liu
2016-07-05 13:13 ` Jerin Jacob
2016-07-05 13:42 ` Yuanhan Liu
2016-07-05 14:09 ` Ferruh Yigit
2016-07-06 16:21 ` Ferruh Yigit
2016-07-07 13:51 ` Ferruh Yigit
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