Re: [boost] [compute] Review

Subject: Re: [boost] [compute] Review
From: John Bytheway (jbytheway+boost_at_[hidden])
Date: 2014-12-31 09:04:21

On 2014-12-30 23:42, Kyle Lutz wrote:
> On Tue, Dec 30, 2014 at 8:33 PM, John Bytheway
> <jbytheway+boost_at_[hidden]> wrote:
>> On 2014-12-29 02:01, Kyle Lutz wrote:
>>> On Sun, Dec 28, 2014 at 7:26 PM, John Bytheway
>>> <jbytheway+boost_at_[hidden]> wrote:
>>>> - It looks like the performance tests don't include the time for copying
>>>> data to (and, where applicable, from) the device.  You should mention
>>>> this on the Performance page.
>>>
>>> I'll add this, though it is very device/system specific. Also, there
>>> is a performance benchmark available in Boost.Compute
>>> ("perf_copy_to_device") which could be used to measure this on your
>>> own system.
>>
>> More on the subject of performance:
>>
>> I ran some of the performance tests on my machine, and I observed
>> something surprising.
>>
>> set_intersection and set_difference are *unbelievably* fast (two orders
>> of magnitude faster than the std:: versions), and yet set_union and
>> set_symmetric_difference are quite slow (maybe twice as slow as std::).
>>  Looking at the code, the four algorithms are very similar.  Have you
>> any idea what causes this huge discrepancy in their speed?
> 
> Very interesting, I'll look into this more. Also, I wasn't the author
> of those particular algorithms. Could you open an issue on the issue
> tracker [1] for this? Please also include the performance numbers you
> got and the device/platform you used.

Done.

John