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% MakeTextureTimingTest
%
% Screen 'MakeTexture' both allocates memory to hold an OpenGL texture and
% loads a MATLAB matrix into the OpenGL texture. TestMakeTextureTiming
% times those two steps separately, reporting the fraction of time which
% MakeTexture spends allocating memory.
%
% On 1GHz G4, MakeTexture spends less than 3% of its time allocating memory.
% Providing separate Screen subfuntions to allocate and fill textures would
% gain little.
%
% see also: PsychTests
% HISTORY
%
% mm/dd/yy
%
% 1/26/05 awi wrote it.
try
%test for a variety of texture sizes up to the screen size.
screenNumber=max(Screen('Screens'));
w=Screen('OpenWindow', screenNumber, [], [], [], 2);
screenRect=Screen('Rect', screenNumber);
screenDimensions=[RectWidth(screenRect), RectHeight(screenRect)];
maxTextureSize=min(screenDimensions);
numTextures=floor(log2(maxTextureSize));
textureSizes=2.^([1:numTextures])+1;
numSamples=10;
%turn on the debugging switch for 'MakeTexture' to record internal
%timing. See the C source to MakeTexture to see at where times are recorded.
%The preference call tells MakeTexture to record timestamps marking internal events into the time list.
Screen('Preference','DebugMakeTexture', 1);
for i=1:numTextures
fprintf(['Step ' int2str(i) ' of ' int2str(numTextures) ': ']);
fprintf(['Timing generation of a ' int2str(textureSizes(i)) 'x' int2str(textureSizes(i)) ' texture:\n']);
fprintf(['Repeating measurement ' int2str(numSamples) ' times; counting ']);
for s=1:numSamples
fprintf(int2str(s));
if s<numSamples
fprintf('.. ');
else
fprintf('.');
end
Screen('ClearTimeList');
t=Screen('MakeTexture',w,magic(textureSizes(i)));
rawTimes=Screen('GetTimeList'); %index by texture, sample, timestamp
zeroRefTimes=rawTimes-rawTimes(1);
timeList(i,s,:)=zeroRefTimes;
%no reason to accumulate textures except to investigate memory loading vs allocation time.
Screen('Close', t);
end
fprintf('\n\n');
end
Screen('Preference','DebugMakeTexture', 0);
catch
Screen('Preference','DebugMakeTexture', 0);
Screen('CloseAll');
psychrethrow(psychlasterror);
end
%Verify that turning off DebugMakeTexture causes values not to accumulate in
%the timing list.
Screen('ClearTimeList');
tFoo=Screen('MakeTexture',w,magic(textureSizes(1)));
if Screen('GetTimeList') > 0
error('Turning off DebugMakeTexture failed to disable debugging in MakeTexture');
end %if
Screen('CloseAll')
%Average measurements and plot results
%When DebugMakeTexture is enabled, each call to MakeTexture generates four
% timestamps at these events:
% timestamp 1: Upon entering the SCREENMakeTexture C function
% timestamp 2: Immediatly before the valloc call to allocate texture memory
% timestamp 3: Immediatly before the valloc call to allocate texture memory
% timestamp 4: Immediatly before exit from SCREENMakeTexture.
%the indices into our result array are:
%timeList( texture size index, repetition index, timestamp index)
[foo, bar, numTimestamps]=size(timeList);
if numTimestamps ~= 4
error('MakeTexture stores more than the expected four timestamps.');
end
%first average across repeated measurements
for tex=1:numTextures
for ts=1:numTimestamps
avgTimes(tex, ts)=mean(timeList(tex, :, ts));
end %for ts
end %for tx
allocationTimes=avgTimes(:,3) - avgTimes(:,2);
meanAllocationTimes=mean(allocationTimes);
copyTimes=avgTimes(:,4) - avgTimes(:,3);
meanCopyTimes=mean(copyTimes);
fprintf('Result:\n');
fprintf(['Average time to allocate texture memory: ' num2str(meanAllocationTimes) ' Secs.\n']);
fprintf(['Average time to copy the MATLAB matrix into the OpenGL texture: ' num2str(meanCopyTimes) ' Secs\n']);
fprintf(['Average proportion of time which MakeTexture spends allocating memory: ' num2str(meanAllocationTimes/meanCopyTimes) '\n']);
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