Re: time to ticks converter optimization in pthread_cond_timedwait

["W. Jensen" <waj4news at cox dot net>]

ok, thanks.

----- Original Message -----
From: "Jonathan Larmour" <jifl@eCosCentric.com>
To: "Wade Jensen" <waj4news@cox.net>
Cc: <ecos-patches@sources.redhat.com>
Sent: Monday, December 09, 2002 7:27 PM
Subject: Re: time to ticks converter optimization in pthread_cond_timedwait


> Wade Jensen wrote:
> > Hello,
> >
> > Here is a patch that makes a simple optimization in
> > pthread_cond_timedwait.  It will only initialize the time to ticks
> > converters on the first call the same way that is done many other places
> > in the code.  It greatly improves the speed of the
> > pthread_cond_timedwait function.
>
> For some reason although I got your patch, and made a few tweaks myself, I
> never checked it in. I'm doing so now (attached).
>
> Jifl
> --
> eCosCentric       http://www.eCosCentric.com/       <info@eCosCentric.com>
> --[ "You can complain because roses have thorns, or you ]--
> --[  can rejoice because thorns have roses." -Lincoln   ]-- Opinions==mine
>


----------------------------------------------------------------------------
----


> Index: ChangeLog
> ===================================================================
> RCS file: /cvs/ecos/ecos/packages/compat/posix/current/ChangeLog,v
> retrieving revision 1.30
> diff -u -5 -p -r1.30 ChangeLog
> --- ChangeLog 26 Nov 2002 18:16:45 -0000 1.30
> +++ ChangeLog 10 Dec 2002 02:26:53 -0000
> @@ -1,5 +1,11 @@
> +2002-12-10  Wade Jensen  <waj4news@cox.net>
> +2002-12-10  Jonathan Larmour  <jifl@eCosCentric.com>
> +
> + * src/mutex.cxx (pthread_cond_timedwait): Initialize clock converters
> + only once ever.
> +
>  2002-11-26  Nick Garnett  <nickg@ecoscentric.com>
>
>   * src/signal.cxx: Changed the three routines added in the last
>   change so that they can be called safely from non-POSIX threads.
>
> Index: src/mutex.cxx
> ===================================================================
> RCS file: /cvs/ecos/ecos/packages/compat/posix/current/src/mutex.cxx,v
> retrieving revision 1.3
> diff -u -5 -p -r1.3 mutex.cxx
> --- src/mutex.cxx 23 May 2002 22:59:59 -0000 1.3
> +++ src/mutex.cxx 10 Dec 2002 02:26:53 -0000
> @@ -39,11 +39,11 @@
>  //####ECOSGPLCOPYRIGHTEND####
>
//==========================================================================
>  //#####DESCRIPTIONBEGIN####
>  //
>  // Author(s):           nickg
> -// Contributors:        nickg, jlarmour
> +// Contributors:        nickg, jlarmour, Wade Jensen
>  // Date:                2000-03-27
>  // Purpose:             POSIX pthread implementation
>  // Description:         This file contains the implementation of the
POSIX pthread
>  //                      functions.
>  //
> @@ -498,16 +498,41 @@ externC int pthread_cond_timedwait (pthr
>
>      PTHREAD_CHECK( cond );
>      PTHREAD_CHECK( mutex );
>      PTHREAD_CHECK( abstime );
>
> -    cyg_tick_count ticks;
> -    struct Cyg_Clock::converter ns_converter, sec_converter;
> -
> -    Cyg_Clock::real_time_clock->get_other_to_clock_converter( 1,
&ns_converter );
> -    Cyg_Clock::real_time_clock->get_other_to_clock_converter( 1000000000,
&sec_converter );
> +    // Only initialize the converters once or they will consume a huge
> +    // amount or runtime.
> +
> +    static struct Cyg_Clock::converter ns_converter;
> +    static struct Cyg_Clock::converter sec_converter;
> +    static volatile cyg_atomic conv_init;
> +    if (!conv_init)
> +    {
>
> +        // Try to avoid unnecessarily locking the scheduler when we are
not
> +        // initializing the converters.  Check the conv_init flag again
to
> +        // avoid race conditions.
> +
> +        struct Cyg_Clock::converter temp_ns_converter,
temp_sec_converter;
> +
> +        Cyg_Clock::real_time_clock
> +            ->get_other_to_clock_converter( 1, &temp_ns_converter );
> +        Cyg_Clock::real_time_clock
> +            ->get_other_to_clock_converter( 1000000000,
&temp_sec_converter );
> +
> +        Cyg_Scheduler::lock();
> +        if (!conv_init)
> +        {
> +            ns_converter = temp_ns_converter;
> +            sec_converter = temp_sec_converter;
> +            conv_init=1;
> +        }
> +        Cyg_Scheduler::unlock();
> +    }
> +
> +    cyg_tick_count ticks;
>      ticks = Cyg_Clock::convert( abstime->tv_sec, &sec_converter );
>      ticks += Cyg_Clock::convert( abstime->tv_nsec, &ns_converter );
>
>      ((Cyg_Condition_Variable *)cond)->wait( *(Cyg_Mutex *)mutex, ticks );
>
>