Calculating the Intertask Signaling Time

#include <Multiprocessing.h>

#include <Types.h>

#include <stdio.h>

#include <stdlib.h>

#include <sioux.h>

#include <math64.h>

#include <DriverServices.h>

enum  {

    aQueue = 0,

    aSemaphore,

    anEvent

} reflectOP;

MPOpaqueID waiterID, postID;

static OSStatus Reflector ( )

{

    void    *p1,*p2,*p3;

    MPEventFlags events;

    while (true)

    {

        switch (reflectOP)

        {

            case aQueue:

                MPWaitOnQueue((MPQueueID) waiterID, &p1, &p2, &p3, kDurationForever);

                break;

            case aSemaphore:

                MPWaitOnSemaphore((MPSemaphoreID) waiterID, kDurationForever);

                break;

            case anEvent:

                MPWaitForEvent((MPEventID) waiterID, &events, kDurationForever);

                break;

            default:

                return -123;

        }

        switch (reflectOP)

        {

            case aQueue:

                MPNotifyQueue((MPQueueID) postID, &p1, &p2, &p3);

                break;

            case aSemaphore:

                MPSignalSemaphore((MPSemaphoreID) postID);

                break;

            case anEvent:

                MPSetEvent((MPEventID) postID, 0x01010101);

                break;

            default:

                return -123;

        }

    }

    return -123;

}

static float HowLong(

    AbsoluteTime endTime,

    AbsoluteTime bgnTime

    )

{

    AbsoluteTime absTime;

    Nanoseconds  nanosec;

    absTime = SubAbsoluteFromAbsolute(endTime, bgnTime);

    nanosec = AbsoluteToNanoseconds(absTime);

    return (float) UnsignedWideToUInt64( nanosec ) / 1000.0;

}

void main ( void )

{

    OSStatus            err;

    MPTaskID            task;

    UInt32              i, count;

    void                *p1,*p2,*p3;

    MPEventFlags events;

    AbsoluteTime nowTime, bgnTime;

    float               uSec;

    char                buff[10];

    /* Set the console window defaults */

    /* (this is a Metrowerks CodeWarrior thing). */

    SIOUXSettings.autocloseonquit    = true;

    SIOUXSettings.asktosaveonclose  = false;

    SIOUXSettings.showstatusline    = false;

    SIOUXSettings.columns           = 100;

    SIOUXSettings.rows              = 20;

    SIOUXSettings.fontsize          = 10;

//  SIOUXSettings.fontid             = monaco;

    SIOUXSettings.standalone         = true;

//  DebugStr ( "\pStarting" );

    /*  Can't get very far without this one. */

    if  (!MPLibraryIsLoaded())

    {

        printf("The MP library did not load.\n");

        return;

    }

    /*  Find the overhead up UpTime. Perform a bunch of calls to average out */

    /*   cache effects. */

    printf("\n");

    bgnTime = UpTime();

    for (i=0; i<16; i++)

    {

        nowTime = UpTime();

    }

    uSec  = HowLong(nowTime, bgnTime);

    uSec /=  16.0;

    printf(" UpTime overhead: %.3f usec \n", uSec);

    /*  Time intertask communication. */

    printf("\n Queues\n");

    reflectOP = aQueue;

    MPCreateQueue((MPQueueID*) &waiterID);

    MPCreateQueue((MPQueueID*) &postID);

    bgnTime = UpTime();

    err = MPCreateTask( Reflector,

                  NULL,

                  0,

                  NULL,

                  0,

                  0,

                  kNilOptions,

                  &task );

    nowTime = UpTime();

    uSec  = HowLong(nowTime, bgnTime);

    printf(" MPCreateTask overhead: %.3f usec (may vary significantly) \n", uSec);

    if (err != noErr)

    {

        printf(" Task not created!\n");

        return;

    }

    count = 100000;

    bgnTime = UpTime();

    for (i=0; i<count; i++)

    {

        MPNotifyQueue((MPQueueID) waiterID, 0, 0, 0);

        while (true)

        {

            err = MPWaitOnQueue((MPQueueID) postID, &p1, &p2, &p3, kDurationImmediate);

            if (err != kMPTimeoutErr) break;

        }

    }

    nowTime = UpTime();

    uSec  = HowLong(nowTime, bgnTime);

    uSec  /= ((float) count / 2.0); // Two trips.

    printf(" Intertask signaling using queues overhead: %.3f usec \n", uSec);

    /*  Time intertask communication.

    */

    MPTerminateTask(task, 123);

    printf("\n Semaphores\n");

    reflectOP = aSemaphore;

    MPCreateSemaphore(1, 0, (MPSemaphoreID*) &waiterID);

    MPCreateSemaphore(1, 0, (MPSemaphoreID*) &postID);

    bgnTime = UpTime();

    err = MPCreateTask( Reflector,

                  NULL,

                  0,

                  NULL,

                  0,

                  0,

                  kNilOptions,

                  &task );

    nowTime = UpTime();

    uSec  = HowLong(nowTime, bgnTime);

    printf(" MPCreateTask overhead: %.3f usec (may vary significantly) \n", uSec);

    if (err != noErr)

    {

        printf(" Task not created!\n");

        return;

    }

    count = 100000;

    bgnTime = UpTime();

    for (i=0; i<count; i++)

    {

        MPSignalSemaphore((MPSemaphoreID) waiterID);

        while (true)

        {

            err = MPWaitOnSemaphore((MPSemaphoreID) postID, kDurationImmediate);

            if (err != kMPTimeoutErr) break;

        }

    }

    nowTime = UpTime();

    uSec  = HowLong(nowTime, bgnTime);

    uSec  /= ((float) count / 2.0); // Two trips.

    printf(" Intertask signaling using semaphores overhead: %.3f usec \n", uSec);

    /*  Time intertask communication. */

    MPTerminateTask(task, 123);

    printf("\n Event Groups\n");

    reflectOP = anEvent;

    MPCreateEvent((MPEventID*) &waiterID);

    MPCreateEvent((MPEventID*) &postID);

    bgnTime = UpTime();

    err = MPCreateTask( Reflector,

                  NULL,

                  0,

                  NULL,

                  0,

                  0,

                  kNilOptions,

                  &task );

    nowTime = UpTime();

    uSec  = HowLong(nowTime, bgnTime);

    printf(" MPCreateTask overhead: %.3f usec (may vary significantly) \n", uSec);

    if (err != noErr)

    {

        printf(" Task not created!\n");

        return;

    }

    count = 100000;

    bgnTime = UpTime();

    for (i=0; i<count; i++)

    {

        MPSetEvent((MPEventID) waiterID, 0x01);

        while (true)

        {

            err = MPWaitForEvent((MPEventID) postID, &events, kDurationImmediate);

            if (err != kMPTimeoutErr) break;

        }

    }

    nowTime = UpTime();

    uSec  = HowLong(nowTime, bgnTime);

    uSec  /= ((float) count / 2.0); // Two trips.

    printf(" Intertask signaling using events overhead: %.3f usec \n", uSec);

    gets(buff);

}