[dpdk-dev] [PATCH 0/3] add new Double Word Key hash table

[Medvedkin, Vladimir]

Hi Morten,


On 16/03/2020 14:39, Morten Brørup wrote:
>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Vladimir Medvedkin
>> Sent: Monday, March 16, 2020 2:38 PM
>>
>> Currently DPDK has a special implementation of a hash table for
>> 4 byte keys which is called FBK hash. Unfortunately its main drawback
>> is that it only supports 2 byte values.
>> The new implementation called DWK (double word key) hash
>> supports 8 byte values, which is enough to store a pointer.
>>
>> It would also be nice to get feedback on whether to leave the old FBK
>> and new DWK implementations, or whether to deprecate the old one?
> <rant on>
>
> Who comes up with these names?!?
>
> FBK (Four Byte Key) and DWK (Double Word Key) is supposed to mean the same. Could you use 32 somewhere in the name instead, like in int32_t, instead of using a growing list of creative synonyms for the same thing? Pretty please, with a cherry on top!


That's true, at first I named it as fbk2, but then it was decided to 
rename it "dwk", so that there was no confusion with the existing FBK 
library. Naming suggestions are welcome!

>
> And if the value size is fixed too, perhaps the name should also indicate the value size.
>
> <rant off>
>
> It's a shame we don't have C++ class templates available in DPDK...
>
> In other news, Mellanox has sent an RFC for an "indexed memory pool" library [1] to conserve memory by using uintXX_t instead of pointers, so perhaps a variant of a 32 bit key hash library with 32 bit values (in addition to 16 bit values in FBK and 64 bit in DWK) would be nice combination with that library.
>
> [1]: http://mails.dpdk.org/archives/dev/2019-October/147513.html
>
>
> Med venlig hilsen / kind regards
> - Morten Brørup
>
-- 
Regards,
Vladimir