Re: [boost] serialization performance

From: Robert Ramey (ramey_at_[hidden])
Date: 2005-11-12 21:08:30

Martin Slater wrote:
>  > I believe the intel machine has hardware instructions which
> implement
>> strcmp and that compilers support them.  So even if strcmp is the
>> bottleneck, I wouldn't expect it to show up on the profiler unless
>> some sort of inlining were turned off.  Or maybe the vtune profiler
>> has special provision for these cases somewhere.
>
> VTune doesn't have any special provision for this, if a function is
> inlined it will just show up in the function it inlined it to. Under
> VC
> by default strcmp is just a regular function call but you can enable
> it
> as a compiler intrinsic (#pragma intrinsic(strcmp) ) and the compiler
> may well then generate much better code (I know enabling memcpy this
> way can reduce memcpy(&a, &b, sizeof(int)) to a simple register mov
> in places).

Hmmm - then the fact it showed up on the profiler suggests that
the program wasn't compiled with full optimisation?  You might
want to expand upon this.

> If your interested in vtune they do an evaluation verion at
> https://registrationcenter.intel.com/EvalCenter/EvalForm.aspx?ProductID=319
> It is simply the best profiling tool I have ever used.

At one time I had the intel eval compiler installed and it was very good.
My license expired and I just didn't have the incentive to actually pay
for it.  Too bad I would have liked to have it my test suite.

> I'd be more than happy to help out with any profiling and
> optimisation I can.

Well, you'll get your chance pretty soon.  Soon I'll be checking in my
test_overhead program into the development tree.  I think I can
pass the compiler switches to get it to generate a profile - at least
for gcc - but I'm struggling to figure out how to get bjam to invoke
gprof to display the profile in the output and to make sure I can
see it in the test matrix.  So you may get your chance to make this
work for vtune.  I'm surprised that profling / bench marking isn't
commonly part of the test suites of boost libraries.

Robert Ramey