Re: data structure lockin

[Richard Mortier <Richard.Mortier@xxxxxxxxxxxxxxxx>]

interesting... thanks! :)

On 16 Jan 2013, at 23:50, Thomas Gazagnaire wrote:

> To be more complete, you also need to carefully tune your "compare" function 
> when you use a purely functional data-structure:
> 
> https://github.com/samoht/ocaml-dns/commit/053c12bcff4287de86fc2e686b21e99e98cd083c
> 
> I'vet passed from 25k qps to 30k qps by just doing this.
> 
> The same trick works with the memoization table:
> 
> https://github.com/samoht/mirage-skeleton/commit/6ed135317f78f4cab580c8e7d1e5d919ff188147
> 
> --
> Thomas
> 
> On Jan 16, 2013, at 10:41 PM, Richard Mortier wrote:
> 
>> nice... :)
>> 
>> On 16 Jan 2013, at 22:38, Anil Madhavapeddy wrote:
>> 
>>> Continuing the topic of data structures, I noticed a slowdown for the DNS 
>>> performance after the recent conversion to cstruct.  While the memoized 
>>> version (which caches marshalled packets) was about the same performance, 
>>> the normal one was much slower (even worse than BIND).
>>> 
>>> Thomas did some profiling today, and it turns out that the use of a mutable 
>>> Hashtbl for tracking label compression results in very bad performance, 
>>> since the string lists all have hash collisions and ends up linearising the 
>>> structure.  He converted it to use a purely functional Map instead (which 
>>> just lives on the minor heap since it's only needed for one packet parse 
>>> cycle), and performance is right back where it should be!
>>> 
>>> https://github.com/samoht/ocaml-dns/commit/fd68be3850353f2fb981b100bf04562ae0d99a1e
>>> 
>>> (mainly fyi for Mort, but useful for others too)
>>> 
>>> -anil
>> 
>> 
>> -- 
>> Cheers,
>> 
>> R.
>> 
>> 
>> 
>> 
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> 


-- 
Cheers,

R.




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