Re: [dpdk-dev] [PATCH v6 0/4] add IOVA = VA support in KNI

From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>,
	Ferruh Yigit <ferruh.yigit@intel.com>,
	Vamsi Krishna Attunuru <vattunuru@marvell.com>,
	"dev@dpdk.org" <dev@dpdk.org>
Cc: "olivier.matz@6wind.com" <olivier.matz@6wind.com>,
	"arybchenko@solarflare.com" <arybchenko@solarflare.com>
Subject: Re: [dpdk-dev] [PATCH v6 0/4] add IOVA = VA support in KNI
Date: Fri, 12 Jul 2019 13:09:51 +0100	[thread overview]
Message-ID: <0ef0c75d-bff6-ac20-61e1-a4a2472fc7f7@intel.com> (raw)
In-Reply-To: <BYAPR18MB2424164D8F69555486FDB55FC8F20@BYAPR18MB2424.namprd18.prod.outlook.com>

On 12-Jul-19 12:37 PM, Jerin Jacob Kollanukkaran wrote:
>> -----Original Message-----
>> From: Burakov, Anatoly <anatoly.burakov@intel.com>
>> Sent: Friday, July 12, 2019 4:19 PM
>> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; Ferruh Yigit
>> <ferruh.yigit@intel.com>; Vamsi Krishna Attunuru
>> <vattunuru@marvell.com>; dev@dpdk.org
>> Cc: olivier.matz@6wind.com; arybchenko@solarflare.com
>> Subject: [EXT] Re: [dpdk-dev] [PATCH v6 0/4] add IOVA = VA support in KNI
>> On 12-Jul-19 11:26 AM, Jerin Jacob Kollanukkaran wrote:
>>>>>> What do you think?
>>>>>
>>>>> IMO, If possible we can avoid extra indirection of new config. In
>>>>> worst case We can add it. How about following to not have new config
>>>>>
>>>>> 1) Make MEMPOOL_F_NO_PAGE_BOUND  as default
>>>>> http://patches.dpdk.org/patch/55277/
>>>>> There is absolutely zero overhead of this flag considering the huge
>>>>> page size are minimum 2MB. Typically 512MB or 1GB.
>>>>> Any one has any objection?
>>>>
>>>> Pretty much zero overhead in hugepage case, not so in non-hugepage
>> case.
>>>> It's rare, but since we support it, we have to account for it.
>>>
>>> That is a fair concern.
>>> How about enable the flag in mempool ONLY when
>> rte_eal_has_hugepages()
>>> In the common layer?
>>
>> Perhaps it's better to check page size of the underlying memory, because 4K
>> pages are not necessarily no-huge mode - they could also be external
>> memory. That's going to be a bit hard because there may not be a way to
>> know which memory we're allocating from in advance, aside from simple
>> checks like `(rte_eal_has_hugepages() ||
>> rte_malloc_heap_socket_is_external(socket_id))` - but maybe those would
>> be sufficient.
> 
> Yes.
> 
> 
>>
>>>
>>>> (also, i don't really like the name NO_PAGE_BOUND since in memzone
>>>> API there's a "bounded memzone" allocation API, and this flag's name
>>>> reads like objects would not be bounded by page size, not that they
>>>> won't cross page
>>>> boundary)
>>>
>>> No strong opinion for the name. What name you suggest?
>>
>> How about something like MEMPOOL_F_NO_PAGE_SPLIT?
> 
> Looks good to me.
> 
> In summary, Change wrt existing patch"
> - Change NO_PAGE_BOUND to MEMPOOL_F_NO_PAGE_SPLIT
> - Set this flag in  rte_pktmbuf_pool_create() when rte_eal_has_hugepages() ||
>   rte_malloc_heap_socket_is_external(socket_id))

If we are to have a special KNI allocation API, would we even need that?

> 
> Olivier, Any objection?
> Ref: http://patches.dpdk.org/patch/55277/
> 

-- 
Thanks,
Anatoly