Re: [dpdk-dev] Huge mapping secondary process linux

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

On 10/27/2017 10:44 PM, Burakov, Anatoly wrote:
> On 27-Oct-17 3:28 PM, Jonas Pfefferle1 wrote:
>> "Burakov, Anatoly" <anatoly.burakov@intel.com> wrote on 10/27/2017 
>> 04:06:44 PM:
>>
>>  > From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
>>  > To: Jonas Pfefferle1 <JPF@zurich.ibm.com>, dev@dpdk.org
>>  > Cc: chaozhu@linux.vnet.ibm.com, bruce.richardson@intel.com
>>  > Date: 10/27/2017 04:06 PM
>>  > Subject: Re: [dpdk-dev] Huge mapping secondary process linux
>>  ...
>>  > >
>>  > hi Jonas,
>>  >
>>  > MAP_FIXED is not used because it's dangerous, it unmaps anything 
>> that is
>>  > already mapped into that space. We would rather know that we can't 
>> map
>>  > something than unwittingly unmap something that was mapped before.
>>
>> Ok, I see. Maybe we can add a check to the primary process's memory 
>> mappings whether the hint has been respected or not? At least warn if 
>> it hasn't.
>
> Hi Jonas,
>
> I'm unfamiliar with POWER platform, so i'm afraid you'd have to 
> explain a bit more what you mean by "hint has been respected" :)

Actually, I also met this case on x86 once that kernel does not respect 
the "addr" parameter even that memory region is not occupied. I am not 
sure if it can be reproduced now, anyway, send here FYI: we run primary 
on the host, run secondary in a container.

I'll agree at least we need to check if the final addr is the same of 
the parameter addr, and warn if it's not.

Thanks,
Jianfeng