On 10/27/2017 10:44 PM, Burakov, Anatoly wrote:

On 27-Oct-17 3:28 PM, Jonas Pfefferle1 wrote:

quoted

"Burakov, Anatoly" [off-list ref] wrote on 10/27/2017 
04:06:44 PM:

 > From: "Burakov, Anatoly" [off-list ref]
 > To: Jonas Pfefferle1 [off-list ref], 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