Re: [Boost-users] [boost.thread] function call and functor in thread creation: performance

Subject: Re: [Boost-users] [boost.thread] function call and functor in thread creation: performance
From: Boost lzw (boostlzw_at_[hidden])
Date: 2011-01-22 07:54:59

I tend to think the job that a thread does is non-trivial. Does this mean
that I should never try to inline the function call operator? Does anyone
know the performance difference between creating a new boost thread via
ordinary function vs. doing that via a functor?

Thanks

On Fri, Jan 21, 2011 at 11:53 PM, Steven Watanabe <watanabesj_at_[hidden]>wrote:

> AMDG
>
>
> On 1/21/2011 5:55 PM, Boost lzw wrote:
>
>> A new thread can be created using boost thread either from a function or a
>> functor as the entry point of the new thread, as:
>>
>> void thread_function();
>> boost::thread thrd(&function);
>>
>> class functor
>> {
>> public:
>>          inline void operator()();
>> };
>> functor f;
>> boost::thread thrd(f);
>>
>> Is there a performance difference between these two?
>>
>> In an ordinary C++ program, can I claim that calling f() 1000 times gives
>> better performance than calling thread_function() 1000 times, because the
>> functor is hinted "inline" even the hint is igored by my compiler? Is f()
>> the same as a function call in term of performance?
>>
>>
> The cost if creating the thread almost
> certainly swamps the function call overhead.
> Even ignoring this, if the work the function
> does is trivial enough that inlining matters,
> then you probably shouldn't be spawning a thread
> for it anyway.
>
> In Christ,
> Steven Watanabe
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