Re: [dpdk-dev] [EXT] Re: ABI and inline functions

[Ray Kinsella <mdr@ashroe.eu>]

On 18/04/2019 06:56, Jerin Jacob Kollanukkaran wrote:
> 
>> -----Original Message-----
>> From: Stephen Hemminger <stephen@networkplumber.org>
>> Sent: Thursday, April 18, 2019 12:21 AM
>> To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
>> Cc: Bruce Richardson <bruce.richardson@intel.com>; Honnappa Nagarahalli
>> <Honnappa.Nagarahalli@arm.com>; dev@dpdk.org; Ananyev, Konstantin
>> <konstantin.ananyev@intel.com>; thomas@monjalon.net; Ray Kinsella
>> <mdr@ashroe.eu>; nd <nd@arm.com>
>> Subject: [EXT] Re: [dpdk-dev] ABI and inline functions
>>> I would value ABI compatibility much higher than API compatibility.
>>>> If someone is recompiling the application anyway, making a couple of
>>>> small changes (large rework is obviously a different issue) to the
>>>> code should not be a massive issue, I hope. On the other hand, ABI
>>>> compatibility is needed to allow seamless update from one version to
>>>> another, and it's that ABI compatiblity that allows distro's to pick up our
>> latest and greatest versions.
>>>
>>> IMO, We have two primary use case for DPDK
>>>
>>> 1) NFV kind of use case 	where the application needs to run on multiple
>> platform
>>> without recompiling it.
>>> 2) Fixed appliance use case where embed SoC like Intel Denverton or
>>> ARM64 integrated Controller used. For fixed appliance use case, end
>>> user care more of performance than ABI compatibility as it easy to
>>> recompile the end user application vs the cost of hitting performance impact.
>>
>> Nobody cares about compatiablity until they have to the first security update.
> 
> For fixed appliance case, The update(FW update) will be  a single blob which
> Include all the components. So they can back port the security fix and recompile
> the sw as needed.
> 
> The very similar category  is DPDK running in smart NICs(Runs as FW in PCIe EP device).

So is there a real versus a perceived compromise happen here - that we
are compromising optimal performance in order to make API stability
happen? Do we have specific an examples that this is actually the case?

Thanks,

Ray K