[dpdk-dev] [PATCH 3/5] mempool: remove optimistic IOVA-contiguous allocation

[Andrew Rybchenko]

On 10/29/19 8:20 PM, Olivier Matz wrote:
> On Tue, Oct 29, 2019 at 01:25:10PM +0300, Andrew Rybchenko wrote:
>> On 10/28/19 5:01 PM, Olivier Matz wrote:
>>> The previous commit reduced the amount of required memory when
>>> populating the mempool with non iova-contiguous memory.
>>>
>>> Since there is no big advantage to have a fully iova-contiguous mempool
>>> if it is not explicitly asked, remove this code, it simplifies the
>>> populate function.
>>>
>>> Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
>> One comment below, other than that
>> Reviewed-by: Andrew Rybchenko <arybchenko at solarflare.com>
>>
>>> ---
>>>    lib/librte_mempool/rte_mempool.c | 47 ++++++--------------------------
>>>    1 file changed, 8 insertions(+), 39 deletions(-)
>>>
>>> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
>>> index 3275e48c9..5e1f202dc 100644
>>> --- a/lib/librte_mempool/rte_mempool.c
>>> +++ b/lib/librte_mempool/rte_mempool.c
>> [snip]
>>
>>> @@ -531,36 +521,15 @@ rte_mempool_populate_default(struct rte_mempool *mp)
>>>    			goto fail;
>>>    		}
>>> -		flags = mz_flags;
>>> -
>>>    		/* if we're trying to reserve contiguous memory, add appropriate
>>>    		 * memzone flag.
>>>    		 */
>>> -		if (try_iova_contig_mempool)
>>> -			flags |= RTE_MEMZONE_IOVA_CONTIG;
>>> +		if (min_chunk_size == (size_t)mem_size)
>>> +			mz_flags |= RTE_MEMZONE_IOVA_CONTIG;
>>>    		mz = rte_memzone_reserve_aligned(mz_name, mem_size,
>>> -				mp->socket_id, flags, align);
>>> -
>>> -		/* if we were trying to allocate contiguous memory, failed and
>>> -		 * minimum required contiguous chunk fits minimum page, adjust
>>> -		 * memzone size to the page size, and try again.
>>> -		 */
>>> -		if (mz == NULL && try_iova_contig_mempool &&
>>> -				min_chunk_size <= pg_sz) {
>>> -			try_iova_contig_mempool = false;
>>> -			flags &= ~RTE_MEMZONE_IOVA_CONTIG;
>>> -
>>> -			mem_size = rte_mempool_ops_calc_mem_size(mp, n,
>>> -					pg_shift, &min_chunk_size, &align);
>>> -			if (mem_size < 0) {
>>> -				ret = mem_size;
>>> -				goto fail;
>>> -			}
>>> +				mp->socket_id, mz_flags, align);
>>> -			mz = rte_memzone_reserve_aligned(mz_name, mem_size,
>>> -				mp->socket_id, flags, align);
>>> -		}
>>>    		/* don't try reserving with 0 size if we were asked to reserve
>>>    		 * IOVA-contiguous memory.
>>>    		 */
>> [snip]
>>
>>> @@ -587,7 +556,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
>>>    		else
>>>    			iova = RTE_BAD_IOVA;
>>> -		if (try_iova_contig_mempool || pg_sz == 0)
>>> +		if (pg_sz == 0)
>> I think (mz_flags & RTE_MEMZONE_IOVA_CONTIG) is lost here.
> Do you mean we should do instead
> 	if (pg_sz == 0 || (mz_flags & RTE_MEMZONE_IOVA_CONTIG))
> 		populate_iova()
> 	else
> 		populate_virt()
> ?

Yes.

> I would say yes, but it should be removed in patch 5/5.
> At the end, we don't want objects to be across pages, even
> with RTE_MEMZONE_IOVA_CONTIG.
>
>>>    			ret = rte_mempool_populate_iova(mp, mz->addr,
>>>    				iova, mz->len,
>>>    				rte_mempool_memchunk_mz_free,