[dpdk-dev] [PATCH] memory: do not use base-virtaddr in secondary processes

[Burakov, Anatoly]

On 18-Jun-18 9:12 PM, Stojaczyk, DariuszX wrote:
> 
> 
>> -----Original Message-----
>> From: Alejandro Lucero [mailto:alejandro.lucero at netronome.com]
>> Sent: Monday, June 18, 2018 9:33 PM
>>
>> On Mon, Jun 18, 2018 at 8:03 PM, Stojaczyk, DariuszX
>> <dariuszx.stojaczyk at intel.com <mailto:dariuszx.stojaczyk at intel.com> >
>> wrote:
>>
>> 	Can you point me out to an NFP guide or some code that describes
>> this in more detail?
>>
>>
>>
>> As I said, I'm working on a RFC. I will send something shortly. But I could give
>> you an advance: the hugepages needs to be mapped below certain virtual
>> address, 1TB, and I'm afraid that includes the primary and also the
>> secondary processes. At least if any process can send or receive packets
>> to/from a NFP.
>>
>>
> 
> Thanks, I'm pretty sure we're safe, then.
> 
>>
>> 	If we're talking about base-virtaddr for hugepages, then that's always
>> inherited from the primary process, regardless of what base-virtaddr is
>> supplied to the secondary.
>>
>>
>>
>>
>> But, is not your patch avoiding to use that base-virtaddr for secondary
>> processes?
> 
> I see now that the patch name is slightly misleading. Maybe I shouldn’t pick such a catchy title. Let me clarify: As of DPDK 18.05, --base-virtaddr param for secondary process applications only affects that shadow memseg metadata that's not useful for anyone, but can still do a lot of harm. Hugepage memory in secondary processes is always mapped to the same addresses the primary process uses.
> 
> D.
> 

Hi Alejandro,

To solve this problem, one possible approach would be to have maximum VA 
address, and allocate memory downwards, rather than upwards. Is that by 
any chance approximate contents of your RFC? :)

-- 
Thanks,
Anatoly