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Tomasz,
Thank you for looking at it.
On my machine, I get the following results:
1,000 Base cycle length:
Loop Overhead = 181us / 1000 bars
Loop Operator = 576us / 1000 bars
10,000 Base cycle length:
Loop Overhead = 240us / 1000 bars
Loop Operator = 1024us / 1000 bars
Best regards,
Dennis
On Jul 4, 2009, at 3:05 PM, Tomasz Janeczko wrote:
> Hello,
>
> I have run your code and results are pretty much the same in both
> settings.
>
> Best regards,
> Tomasz Janeczko
> amibroker.com
>
> Dennis Brown wrote:
>> Hello Tomasz,
>>
>> Below is some AFL I wrote to explore the speed difference between
>> Array and Loop operations. I wanted to explore a number of different
>> array operations to see if I could speed up my indicators.
>>
>> It shows the difference in speed for finding the highest value in a
>> whole array.
>> I am not sure my math is correct though, because one of the results
>> seem counter intuitive.
>>
>> For instance:
>>
>> I test a for() loop that does nothing in order to get the loop
>> overhead. I subtract that number from the loop that is doing the
>> real
>> operation to get just the time to do the one operation. I subtracted
>> off the loop overhead because a loop will usually have a lot of
>> operations that spread out the overhead. I do this for 1,000 cycles
>> and for 10,000 cycles.
>>
>> I would expect the time to execute a single AFL line after
>> subtracting
>> off the overhead would be the same regardless of the number of
>> cycles. However, the results say that it takes almost twice as long
>> to execute that operation in a 1,000 cycle loop than a 10,000 cycle
>> loop. Since this is not what I would expect, so I have to assume I
>> did something wrong. I figured I should ask for a review before
>> making statements about how much faster arrays are.
>>
>> On the other hand, the array operation shows almost one third of the
>> time per bar when going from 1,000 to 10,000 bars, which is
>> reasonable.
>>
>> Am I missing something in my understanding, or am I just a lousy AFL
>> coder? :)
>>
>> Best regards,
>> Dennis
>>
>> /*
>> ////////////////////////////////////////////////////////////////////////////////////////
>> // Simple test code to show speed difference between loop and array
>> operations -- 7/4/2009 Dennis Brown
>> // Edit this AFL for each comparison of equivelent operations
>> // Check both 1000 and 10,000 bar operations to derive the overhead
>> // Timing on one pass is jumpy, so it will avarage passes for a large
>> term average -- just wait a while
>> // Watch out for differences in operation lengths due to one way
>> nature of SetBarsRequired()
>> // Do the short cycle length first, then the long one, then edit AFL
>> with short one selected to reset SBR -- what a pain
>> // If I could switch to lower SBR numbers on the fly, I could
>> calculate a complete curve with overheads
>> // Number of bars loaded seems to always be 200 more than the
>> requested number with SBR
>> // Interestingly, //comments seem to run a little faster than /*
>> comments */ in the timing loop
>> */
>> LoopText = ArrayText = ""; // init and make global
>>
>> function LoopOperation( Length ) { /* Edit this function with the
>> loop
>> operator to be tested */
>> GetPerformanceCounter( True ); /* reset the timer */
>> MaxPrice = 0;
>> for ( i=0; i<Length; i++ ) {
>> /* insert the loop operation(s) to be tested below */
>> MaxPrice = Max( MaxPrice, C[i] );
>> }
>> LoopText = "MaxPrice = Max( MaxPrice, C[i] );" ; /* duplicate
>> operator here for display output */
>> return round(1000000/Length*GetPerformanceCounter( False ) ); /*
>> returns time in microseconds per 1000 */
>> }
>>
>> function ArrayOperation( Length ) { /* Edit this function with the
>> array operator to be tested */
>> GetPerformanceCounter( True ); /* reset the timer */
>> MaxPrice = LastValue( HHV( C, Length ) );
>> ArrayText = "MaxPrice = LastValue( HHV( C, Length ) );" ; /*
>> duplicate operator here for display output */
>> return round(1000000/Length*GetPerformanceCounter( False ) ); /*
>> returns time in microseconds per 1000 */
>> }
>>
>> function LoopOverhead( Length ) { /* loop overhead to be tested, do
>> NOT edit */
>> GetPerformanceCounter( True ); /* reset the timer */
>> for ( i=0; i<Length; i++ ) { ; }
>> return round(1000000/Length*GetPerformanceCounter( False ) ); /*
>> returns time in microseconds per 1000 */
>> }
>>
>> // main routine
>> LastSBRLength = StaticVarGet( "LastSBRParameterValue" );
>> SBRLength = Param( "Base cycle length", 1000, 1000, 10000, 9000 );
>> Length = BarCount-200;
>> if ( ParamTrigger("Reset Averages", "Click to Reset" ) OR
>> LastSBRLength != SBRLength OR Length != SBRLength ) {
>> StaticVarSet( "TimeSum0", 0 );
>> StaticVarSet( "TimeSum1", 0 );
>> StaticVarSet( "TimeSum2", 0 );
>> StaticVarSet( "TimeCycles", 0 );
>> StaticVarSet( "LastSBRParameterValue", SBRLength );
>> Title = " Warning -- SetBarsRequired() can not reduce bars -- Edit
>> AFL to reset SBR or increase length parameter";
>> }
>> else { // only execute the code if all the bar requirements match so
>> we get accurate results (i.e., first cycle is all bars)
>>
>> TimeSum0 = StaticVarGet( "TimeSum0" );
>> TimeSum1 = StaticVarGet( "TimeSum1" );
>> TimeSum2 = StaticVarGet( "TimeSum2" );
>> TimeCycles = 1 + StaticVarGet( "TimeCycles" );
>>
>> TimeSum0 += LoopOverhead( Length ); // loop overhead to be tested
>> TimeSum1 += LoopOperation( Length ); // loop operator to be tested
>> TimeSum2 += ArrayOperation( Length ); // array operator to be tested
>>
>> StaticVarSet( "TimeSum0", TimeSum0 );
>> StaticVarSet( "TimeSum1", TimeSum1 );
>> StaticVarSet( "TimeSum2", TimeSum2 );
>> StaticVarSet( "TimeCycles", TimeCycles );
>>
>> Time0 = round( TimeSum0 / TimeCycles );
>> Time1 = round( TimeSum1 / TimeCycles );
>> Time2 = round( TimeSum2 / TimeCycles );
>>
>> OpTime = Time1-Time0; // subtract off the constant loop overhead
>> speedup = NumToStr( OpTime /Time2, 0.1 );
>> if ( Length != SBRLength ) { warning = " !!! Warning Length
>> Mismatch !!!"; } else { warning = ""; }
>>
>> Title = "Per 1000 bars (cycles) Tming Test\n" +
>> "Bars Loaded = " + BarCount + "\n" +
>> "Base Cycle Length = " + Length + warning + "\n\n" +
>> "Looped Operation: " + LoopText +
>> "\n\n" +
>> "Loop Overhead = " + time0 + "us\n" +
>> "Looped Operator = " + OpTime + "us\n\n" +
>> "Array Operation: " + ArrayText +
>> "\n\n" +
>> "Array Operator = " + time2 + "us\n" +
>> "Speedup Factor = " + speedup;
>>
>> } // end of active code
>>
>> RequestTimedRefresh( 1 );
>> //Override all bar requirements for our test
>> SetBarsRequired( SBRLength, sbrAll );
>>
>>
>>
>> ------------------------------------
>>
>> **** IMPORTANT PLEASE READ ****
>> This group is for the discussion between users only.
>> This is *NOT* technical support channel.
>>
>> TO GET TECHNICAL SUPPORT send an e-mail directly to
>> SUPPORT {at} amibroker.com
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>> TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
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>>
>>
>>
>>
>
>
> ------------------------------------
>
> **** IMPORTANT PLEASE READ ****
> This group is for the discussion between users only.
> This is *NOT* technical support channel.
>
> TO GET TECHNICAL SUPPORT send an e-mail directly to
> SUPPORT {at} amibroker.com
>
> TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
> http://www.amibroker.com/feedback/
> (submissions sent via other channels won't be considered)
>
> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> Yahoo! Groups Links
>
>
>
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