アップル金属マトリックス乗算ベンチマーク結果は

Question

私はここにアップル金属マトリックス乗算サンプルしようとしている

： https://developer.apple.com/library/ios/samplecode/MetalPartialSumsCompute/Introduction/Intro.html

を私は奇妙な結果を得る：テストでは、[1] - [7]、私は、金属の周りに0.05で動作してもらいますGFlops。テスト[8]〜[20]から、Metalは約500GFlopsで非常に高速に動き出します。私は以下のログを添付します。私はコードを見て、テストの間に違いはありません、彼らはすべて同じサイズのランダムな行列です。ある時点でMetalが何の理由もなく急速に始まるように見える。何が起きているのか？

ログイン：

2016-06-30 16:13:29.609 MetalMatrixMultiplication-iOS[3459:742844] >> [1] Matrix Dimensions: A = [841 x 2012], B = [2012 x 554], C = [841 x 554], lda = 848, ldb = 560, ldc = 560 
>> [1] Accelerate 6.934929 gflops/sec, Metal 0.044756 gflops/sec, Accelerate 27.034708 millisecs, Metal 4189.027417 millisecs, Diff 1.369554e-01 

2016-06-30 16:13:31.747 MetalMatrixMultiplication-iOS[3459:742844] >> [2] Matrix Dimensions: A = [721 x 432], B = [432 x 1436], C = [721 x 1436], lda = 728, ldb = 1440, ldc = 1440 
>> [2] Accelerate 1.405928 gflops/sec, Metal 0.045415 gflops/sec, Accelerate 63.626833 millisecs, Metal 1969.722500 millisecs, Diff 4.248900e-02 

2016-06-30 16:13:34.820 MetalMatrixMultiplication-iOS[3459:742844] >> [3] Matrix Dimensions: A = [1362 x 457], B = [457 x 1078], C = [1362 x 1078], lda = 1368, ldb = 1080, ldc = 1080 
>> [3] Accelerate 1.754547 gflops/sec, Metal 0.046793 gflops/sec, Accelerate 76.485125 millisecs, Metal 2867.863083 millisecs, Diff 3.673622e-02 

2016-06-30 16:13:45.549 MetalMatrixMultiplication-iOS[3459:742844] >> [4] Matrix Dimensions: A = [1783 x 1901], B = [1901 x 1347], C = [1783 x 1347], lda = 1784, ldb = 1352, ldc = 1352 
>> [4] Accelerate 6.528442 gflops/sec, Metal 0.091166 gflops/sec, Accelerate 139.869000 millisecs, Metal 10016.091333 millisecs, Diff 5.854867e-02 

2016-06-30 16:13:48.912 MetalMatrixMultiplication-iOS[3459:742844] >> [5] Matrix Dimensions: A = [709 x 600], B = [600 x 1683], C = [709 x 1683], lda = 712, ldb = 1688, ldc = 1688 
>> [5] Accelerate 2.629253 gflops/sec, Metal 0.045250 gflops/sec, Accelerate 54.460208 millisecs, Metal 3164.426333 millisecs, Diff 4.654048e-02 

2016-06-30 16:13:57.534 MetalMatrixMultiplication-iOS[3459:742844] >> [6] Matrix Dimensions: A = [636 x 1573], B = [1573 x 1942], C = [636 x 1942], lda = 640, ldb = 1944, ldc = 1944 
>> [6] Accelerate 7.106906 gflops/sec, Metal 0.047387 gflops/sec, Accelerate 54.674458 millisecs, Metal 8199.887292 millisecs, Diff 7.446345e-02 

2016-06-30 16:14:10.669 MetalMatrixMultiplication-iOS[3459:742844] >> [7] Matrix Dimensions: A = [1803 x 1689], B = [1689 x 1950], C = [1803 x 1950], lda = 1808, ldb = 1952, ldc = 1952 
>> [7] Accelerate 6.759199 gflops/sec, Metal 0.096267 gflops/sec, Accelerate 175.709292 millisecs, Metal 12337.145375 millisecs, Diff 4.568898e-02 

2016-06-30 16:14:10.878 MetalMatrixMultiplication-iOS[3459:742844] >> [8] Matrix Dimensions: A = [416 x 749], B = [749 x 2034], C = [416 x 2034], lda = 416, ldb = 2040, ldc = 2040 
>> [8] Accelerate 3.589321 gflops/sec, Metal 220.343105 gflops/sec, Accelerate 35.313750 millisecs, Metal 0.575250 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:11.003 MetalMatrixMultiplication-iOS[3459:742844] >> [9] Matrix Dimensions: A = [657 x 716], B = [716 x 734], C = [657 x 734], lda = 664, ldb = 736, ldc = 736 
>> [9] Accelerate 2.946337 gflops/sec, Metal 102.394388 gflops/sec, Accelerate 23.438083 millisecs, Metal 0.674417 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:11.124 MetalMatrixMultiplication-iOS[3459:742844] >> [10] Matrix Dimensions: A = [446 x 945], B = [945 x 707], C = [446 x 707], lda = 448, ldb = 712, ldc = 712 
>> [10] Accelerate 3.426099 gflops/sec, Metal 94.259957 gflops/sec, Accelerate 17.394667 millisecs, Metal 0.632250 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:11.533 MetalMatrixMultiplication-iOS[3459:742844] >> [11] Matrix Dimensions: A = [935 x 1286], B = [1286 x 1899], C = [935 x 1899], lda = 936, ldb = 1904, ldc = 1904 
>> [11] Accelerate 6.185983 gflops/sec, Metal 441.997324 gflops/sec, Accelerate 73.824208 millisecs, Metal 1.033208 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:11.685 MetalMatrixMultiplication-iOS[3459:742844] >> [12] Matrix Dimensions: A = [541 x 956], B = [956 x 960], C = [541 x 960], lda = 544, ldb = 960, ldc = 960 
>> [12] Accelerate 3.805037 gflops/sec, Metal 153.253113 gflops/sec, Accelerate 26.097417 millisecs, Metal 0.647958 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:12.007 MetalMatrixMultiplication-iOS[3459:742844] >> [13] Matrix Dimensions: A = [1278 x 1809], B = [1809 x 500], C = [1278 x 500], lda = 1280, ldb = 504, ldc = 504 
>> [13] Accelerate 7.661287 gflops/sec, Metal 343.033372 gflops/sec, Accelerate 30.176417 millisecs, Metal 0.673958 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:12.456 MetalMatrixMultiplication-iOS[3459:742844] >> [14] Matrix Dimensions: A = [1933 x 1534], B = [1534 x 805], C = [1933 x 805], lda = 1936, ldb = 808, ldc = 808 
>> [14] Accelerate 7.221810 gflops/sec, Metal 696.681127 gflops/sec, Accelerate 66.105417 millisecs, Metal 0.685250 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:12.552 MetalMatrixMultiplication-iOS[3459:742844] >> [15] Matrix Dimensions: A = [291 x 645], B = [645 x 1034], C = [291 x 1034], lda = 296, ldb = 1040, ldc = 1040 
>> [15] Accelerate 2.155479 gflops/sec, Metal 62.162540 gflops/sec, Accelerate 18.007750 millisecs, Metal 0.624417 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:12.940 MetalMatrixMultiplication-iOS[3459:742844] >> [16] Matrix Dimensions: A = [1656 x 1547], B = [1547 x 781], C = [1656 x 781], lda = 1656, ldb = 784, ldc = 784 
>> [16] Accelerate 7.341706 gflops/sec, Metal 424.495925 gflops/sec, Accelerate 54.504792 millisecs, Metal 0.942667 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:13.425 MetalMatrixMultiplication-iOS[3459:742844] >> [17] Matrix Dimensions: A = [1651 x 1320], B = [1320 x 1429], C = [1651 x 1429], lda = 1656, ldb = 1432, ldc = 1432 
>> [17] Accelerate 6.615108 gflops/sec, Metal 1001.902932 gflops/sec, Accelerate 94.155625 millisecs, Metal 0.621667 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:13.757 MetalMatrixMultiplication-iOS[3459:742844] >> [18] Matrix Dimensions: A = [2037 x 384], B = [384 x 1615], C = [2037 x 1615], lda = 2040, ldb = 1616, ldc = 1616 
>> [18] Accelerate 1.737157 gflops/sec, Metal 331.366545 gflops/sec, Accelerate 145.440583 millisecs, Metal 0.762458 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:13.923 MetalMatrixMultiplication-iOS[3459:742844] >> [19] Matrix Dimensions: A = [795 x 677], B = [677 x 1145], C = [795 x 1145], lda = 800, ldb = 1152, ldc = 1152 
>> [19] Accelerate 3.405232 gflops/sec, Metal 192.017503 gflops/sec, Accelerate 36.194667 millisecs, Metal 0.641875 millisecs, Diff 0.000000e+00 

2016-06-30 16:14:14.033 MetalMatrixMultiplication-iOS[3459:742844] >> [20] Matrix Dimensions: A = [1062 x 438], B = [438 x 678], C = [1062 x 678], lda = 1064, ldb = 680, ldc = 680 
>> [20] Accelerate 2.090133 gflops/sec, Metal 98.388385 gflops/sec, Accelerate 30.177583 millisecs, Metal 0.641083 millisecs, Diff 0.000000e+00 

Answer 1

何が起こっているが、操作が失敗しているということですが、デモコードは、状態をチェックしません、それは非常に速く走るかのようにのでそれが表示されます。

エラーが発生したとき、あなたがMetalMatrixMult仕上げ方法（MetalMatrixMult.mmライン513）の終わりに、このブロック

if (m_CmdBuffer.status == MTLCommandBufferStatusError) { 
     NSLog(@"Error occured when executing command buffer"); 
     NSLog(@"Error code: %@", mCmdBuffer.error); 
} 

を追加する場合は、表示されます。 エラーコード：

エラードメイン= MTLCommandBufferErrorDomainコード= 2 "引き起こさGPUタイムアウトエラー（IOAFコード2）" のUserInfo = {NSLocalizedDescription =引き起こさGPUタイムアウトエラー（IOAFコード2）}

それは最初で失敗します

次いで、それらの結合後にレポート：

エラーコード：エラードメイン= MTLCommandBufferErrorDomainコード= 4 "は無視（IOAFコード4）（前/過剰GPUエラーを引き起こすための）" のUserInfo = {NSLocalizedDescription =無視される（先行/過度のGPUエラーを引き起こすため）（IOAFコード4）}

iOS 9のMetalで気づいたもう一つのことは、GPUフレームキャプチャとメタルAPI検証が有効になっているときにメモリ管理のバグがあるようだということです（Edit Scheme - > Optionsタブ）。これは、このモードで実行しているときにメタルバッファが割り当て解除されていないかのようです。