Re: [boost] Boost.Variant swap performance

Subject: Re: [boost] Boost.Variant swap performance
From: David Sankel (camior_at_[hidden])
Date: 2012-04-20 18:41:59

It looks like someone else ran into this, but there weren't any responses:

http://lists.boost.org/boost-users/2009/06/49263.php

On Fri, Apr 20, 2012 at 4:29 PM, David Sankel <camior_at_[hidden]> wrote:

> I tried adding a Boost.Move optimized version and while this helped, I'm
> still not getting O(1) performance.
>
> void ilPushFront3( IntList & il, int i )
> {
>     il = IntList
>         ( std::make_pair
>             ( i
>             , ::boost::move( il )
>             )
>         )
>         ;
> }
>
> unoptimized ilPushFront: 115
> unoptimized ilPushFront w/ larger list: 350
> optimized ilPushFront: 217
> optimized ilPushFront w/ larger list: 663
> move optimized ilPushFront: 121
> move optimized ilPushFront w/ larger list: 368
>
> On Fri, Apr 20, 2012 at 3:57 PM, David Sankel <camior_at_[hidden]> wrote:
>
>> It seems as though Boost.Variant doesn't take advantage of pointer swaps
>> when it comes to use of recursive variants. In the attached file I declare
>> a simple int list type and include two implementations of a function that
>> adds an int to the front of a list. The first implementation, I would
>> expect to be O(N) on the size of the list and the second implementation to
>> be O(1) on the size of the list.
>>
>> Unfortunately, the output I get is:
>>
>> unoptimized ilPushFront: 129
>> unoptimized ilPushFront w/ larger list: 363
>> optimized ilPushFront: 211
>> optimized ilPushFront w/ larger list: 653
>>
>>
>> Any ideas why this might be happening?
>>
>> David
>>
>> --
>> David Sankel
>> Sankel Software
>> www.sankelsoftware.com
>> 585 617 4748 (Office)
>>
>
>
>
> --
> David Sankel
> Sankel Software
> www.sankelsoftware.com
> 585 617 4748 (Office)
>

-- 
David Sankel
Sankel Software
www.sankelsoftware.com
585 617 4748 (Office)