From: Andrew Rybchenko <arybchenko@solarflare.com>
To: santosh <santosh.shukla@caviumnetworks.com>,
Olivier Matz <olivier.matz@6wind.com>
Cc: <dev@dpdk.org>, <stable@dpdk.org>, <jerin.jacob@caviumnetworks.com>
Subject: Re: [dpdk-stable] [dpdk-dev] [RFC v2 01/17] mempool: fix phys contig check if populate default skipped
Date: Thu, 1 Feb 2018 13:00:12 +0300 [thread overview]
Message-ID: <618e4eb2-e66c-592c-2065-f86328916d5d@solarflare.com> (raw)
In-Reply-To: <53796b3f-b2c2-dcfc-a10b-71ce1a68d3d2@caviumnetworks.com>
On 02/01/2018 12:30 PM, santosh wrote:
> On Thursday 01 February 2018 02:48 PM, Andrew Rybchenko wrote:
>> On 02/01/2018 12:09 PM, santosh wrote:
>>> On Thursday 01 February 2018 12:24 PM, Andrew Rybchenko wrote:
>>>> On 02/01/2018 08:05 AM, santosh wrote:
>>>>> On Wednesday 31 January 2018 10:15 PM, Olivier Matz wrote:
>>>>>> On Tue, Jan 23, 2018 at 01:15:56PM +0000, Andrew Rybchenko wrote:
>>>>>>> There is not specified dependency between rte_mempool_populate_default()
>>>>>>> and rte_mempool_populate_iova(). So, the second should not rely on the
>>>>>>> fact that the first adds capability flags to the mempool flags.
>>>>>>>
>>>>>>> Fixes: 65cf769f5e6a ("mempool: detect physical contiguous objects")
>>>>>>> Cc: stable@dpdk.org
>>>>>>>
>>>>>>> Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
>>>>>> Looks good to me. I agree it's strange that the mp->flags are
>>>>>> updated with capabilities only in rte_mempool_populate_default().
>>>>>> I see that this behavior is removed later in the patchset since the
>>>>>> get_capa() is removed!
>>>>>>
>>>>>> However maybe this single patch could go in 18.02.
>>>>>> +Santosh +Jerin since it's mostly about Octeon.
>>>>> rte_mempool_xmem_size should return correct size if MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS flag
>>>>> is set in 'mp->flags'. Thats why _ops_get_capabilities() called in _populate_default() but not
>>>>> at _populate_iova().
>>>>> I think, this 'alone' patch may break octeontx mempool.
>>>> The patch does not touch rte_mempool_populate_default().
>>>> _ops_get_capabilities() is still called there before
>>>> rte_mempool_xmem_size(). The theoretical problem which
>>>> the patch tries to fix is the case when
>>>> rte_mempool_populate_default() is not called at all. I.e. application
>>>> calls _ops_get_capabilities() to get flags, then, together with
>>>> mp->flags, calls rte_mempool_xmem_size() directly, allocates
>>>> calculated amount of memory and calls _populate_iova().
>>>>
>>> In that case, Application does like below:
>>>
>>> /* Get mempool capabilities */
>>> mp_flags = 0;
>>> ret = rte_mempool_ops_get_capabilities(mp, &mp_flags);
>>> if ((ret < 0) && (ret != -ENOTSUP))
>>> return ret;
>>>
>>> /* update mempool capabilities */
>>> mp->flags |= mp_flags;
>> Above line is not mandatory. "mp->flags | mp_flags" could be simply
>> passed to rte_mempool_xmem_size() below.
>>
> That depends and again upto application requirement, if app further down
> wants to refer mp->flags for _align/_contig then better update to mp->flags.
>
> But that wasn't the point of discussion, I'm trying to understand that
> w/o this patch, whats could be the application level problem?
The problem that it is fragile. If application does not use
rte_mempool_populate_default() it has to care about addition
of mempool capability flags into mempool flags. If it is not done,
rte_mempool_populate_iova/virt/iova_tab() functions will work
incorrectly since F_CAPA_PHYS_CONTIG and
F_CAPA_BLK_ALIGNED_OBJECTS are missing.
The idea of the patch is to make it a bit more robust. I have no
idea how it can break something. If capability flags are already
there - no problem. If no, just make sure that we locally have them.
next prev parent reply other threads:[~2018-02-01 10:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1511539591-20966-1-git-send-email-arybchenko@solarflare.com>
[not found] ` <1516713372-10572-1-git-send-email-arybchenko@solarflare.com>
2018-01-23 13:15 ` [dpdk-stable] " Andrew Rybchenko
2018-01-31 16:45 ` Olivier Matz
2018-02-01 5:05 ` santosh
2018-02-01 6:54 ` Andrew Rybchenko
2018-02-01 9:09 ` santosh
2018-02-01 9:18 ` [dpdk-stable] [dpdk-dev] " Andrew Rybchenko
2018-02-01 9:30 ` santosh
2018-02-01 10:00 ` Andrew Rybchenko [this message]
2018-02-01 10:14 ` Olivier Matz
2018-02-01 10:33 ` santosh
2018-02-01 14:02 ` Andrew Rybchenko
2018-02-01 10:17 ` santosh
2018-02-01 14:02 ` [dpdk-stable] [PATCH] " Andrew Rybchenko
2018-02-05 23:53 ` Thomas Monjalon
[not found] ` <1521994855-8808-1-git-send-email-arybchenko@solarflare.com>
2018-03-25 16:20 ` [dpdk-stable] [PATCH v2 01/11] mempool: fix memhdr leak when no objects are populated Andrew Rybchenko
[not found] ` <1522080591-24705-1-git-send-email-arybchenko@solarflare.com>
2018-03-26 16:09 ` [dpdk-stable] [PATCH v3 " Andrew Rybchenko
2018-04-06 15:50 ` Olivier Matz
[not found] ` <1523885080-17168-1-git-send-email-arybchenko@solarflare.com>
2018-04-16 13:24 ` [dpdk-stable] [PATCH v4 " Andrew Rybchenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=618e4eb2-e66c-592c-2065-f86328916d5d@solarflare.com \
--to=arybchenko@solarflare.com \
--cc=dev@dpdk.org \
--cc=jerin.jacob@caviumnetworks.com \
--cc=olivier.matz@6wind.com \
--cc=santosh.shukla@caviumnetworks.com \
--cc=stable@dpdk.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).