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: sta...@dpdk.org
>>>>>>
>>>>>> Signed-off-by: Andrew Rybchenko <arybche...@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?
