[dpdk-dev] [PATCH 2/4] mem: add API to obstain memory-backed file info

Sergio Gonzalez Monroy sergio.gonzalez.monroy at intel.com
Tue Jan 12 15:13:21 CET 2016

On 12/01/2016 13:57, Pavel Fedin wrote:
>   Hello!
>> I might be missing something obvious here but, aside from having memory
>> SHARED which most DPDK apps using hugepages will have anyway, what is
>> the backward compatibility issues that you see here?
>   Heh, sorry once again for confusing. Indeed, with hugepages we always get MAP_SHARED. I missed that. So, we indeed need
> --shared-mem only in addition to --no-huge.
>   Backwards compatibility issue is stated in the description of PATCH 1/4:
> --- cut ---
> b. possible ABI break, originally, --no-huge uses anonymous memory
> instead of file-backed way to create memory.
> --- cut ---
>   The patch unconditionally changes that to SHARED. That's all.

I should read more carefully!
Sorry about that, I thought you were the one with the ABI concerns.

Regarding ABI, I don't think there is any ABI issue with the change, we 
just have our memory file-backed and SHARED but we do that when using 
hugepages so I don't think it would be a huge issue.
But if folks have concerns about it, we could always keep old behavior 
by default and, as you suggest, introduce another option for changing 
the flag.

> Kind regards,
> Pavel Fedin
> Senior Engineer
> Samsung Electronics Research center Russia

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