From: santosh <santosh.shukla@caviumnetworks.com>
To: Andrew Rybchenko <arybchenko@solarflare.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 15:47:29 +0530 [thread overview]
Message-ID: <37391638-fa88-4e50-d4a9-f83e24dc2667@caviumnetworks.com> (raw)
In-Reply-To: <618e4eb2-e66c-592c-2065-f86328916d5d@solarflare.com>
On Thursday 01 February 2018 03:30 PM, Andrew Rybchenko wrote:
> 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,
Capability flags should get updated to mempool flags. Or else
_get_ops_capabilities() to update capa flags to mempool flags internally,
I recall that I proposed same in the past.
[...]
> 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.
>
I would prefer _get_ops_capabilities() updates capa flags to mp->flag for once,
rather than doing (mp->flags | mp_flags) across mempool func.
next prev parent reply other threads:[~2018-02-01 10:17 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
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 [this message]
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
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