Re: [boost] [xpressive] Performance Tuning?

Subject: Re: [boost] [xpressive] Performance Tuning?
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2009-07-28 20:56:46

On Tue, Jul 28, 2009 at 11:09 AM, Edward Grace<ej.grace_at_[hidden]> wrote:
>> When I compile and run the tests now, I get this:
>> initializing input strings...
>> Calibrating overhead......done
>> Timer overhead (t_c) ~= : 12
>> Jitter               ~= : 8.43769e-015
>> qi_parse vs atoi    : 170.429 170.438 170.482% faster.
>> qi_parse vs strtol  : 167.589 167.601 167.668% faster.
>> strtol vs atoi      : 1.04669 1.05746 1.06165% faster.
>> qi_parse vs qi_parse : 0 0 0% faster.
>
> Hi OvermindDL1,
>
> When you've woken up would you mind taking a quick squiz at the following
> (anyone else - please feel free)
>
>  ejg_uint_parser_0_0_4_bind_1.cpp
>
> in the following part of Boost Vault, http://tinyurl.com/lro5ok
>
> It's an attempt to crystallise the boo-boo you pointed out.    I've tried to
> do everything without ghastly global variables - it's also a salient lesson
> on const correctness.  If that'd been observed in the first place the
> iterator cock-up wouldn't have happened.
>
>
> ==================
> $ ./ejg_uint_parser
> Enter buffer size: 10000
> initializing input strings...
>
>
>
> Checking that the parsers are functioning  correctly...
> atoi is behaving itself!
> strtol is behaving itself!
> qi is behaving itself!
>
> Proceeding to timing tests.Calibrating overhead......done
> Timer overhead (t_c) ~= : 117.426
> Jitter               ~= : 25.9133
> qi_parse vs atoi    : 86.0764 86.3074 86.4471% faster.
> qi_parse vs strtol  : 71.9253 72.1881 72.5288% faster.
> strtol vs atoi      : 8.0502 8.26097 8.47215% faster.
> qi_parse vs qi_parse : -0.0274542 0.0393936 0.231944% faster.
>
>
> All done!
> ====================
>
>
> On my platform this is entirely consistent with the simple one-liner
> modification you mentioned to the previous code.
>
> Take home message - yes Spirit really *is* faster.

Enter buffer size: 10000
initializing input strings...

Checking that the parsers are functioning  correctly...
atoi is behaving itself!
strtol is behaving itself!
qi is behaving itself!

Proceeding to timing tests.Calibrating overhead......done
Timer overhead (t_c) ~= : 12
Jitter               ~= : 8.43769e-015
qi_parse vs atoi     : 160.834 187.892 197.781% faster.
qi_parse vs strtol  : 152.088 173.709 197.184% faster.
strtol vs atoi       : 5.34019 7.29527 9.82952% faster.
qi_parse vs qi_parse : -3.12862 -0.194198 1.53912% faster.

All done!

MSVC definitely compiles templates code better then GCC it seems (you
said you were using GCC yes?).

Also, I think I might know why QI is faster then atoi/strtol.
atoi/strtol handle local as I recall, QI does not...