继续我的教堂冒险...
我有一个矩阵A。
var idx = {1..n};
var adom = {idx, idx};
var A: [adom] int;
//populate A;
var rowsums: [idx] int;
填充行和的最有效方法是什么？
问问题
95 次
2 回答
2
最有效的解决方案很难定义。但是，这是一种rowsums并行且优雅的计算方法：
config const n = 8; // "naked" n would cause compilation to fail
const indices = 1..n; // tio.chpl:1: error: 'n' undeclared (first use this function)
const adom = {indices, indices};
var A: [adom] int;
// Populate A
[(i,j) in adom] A[i, j] = i*j;
var rowsums: [indices] int;
forall i in indices {
rowsums[i] = + reduce(A[i, ..]);
}
writeln(rowsums);
请注意， 和 都在forall上面+ reduce的程序中引入了并行性。如果 的大小足够小，则仅使用for循环可能会更有效，从而避免产生任务的开销。indices
于 2017-08-16T23:12:31.280 回答
1
使代码在和模式下
实际运行的一些提示：SEQPAR
除了一些实现细节之外，上述@bencray关于假定的设置的间接费用的假设PAR可能有利于设置中的纯串行处理SEQ，但尚未得到实验证实。在这里还需要注意的是，由于明显的原因，分布式模式没有在现场<TiO>-IDE进行测试，而小规模的分布式实现则远非一个有科学意义的实验，而是一个矛盾的说法。
事实很重要
一个rowsums[]处理，即使在最小可能的规模下2x2，在SEQ模式下也比在模式下的256x256处理要慢PAR。
干得好，教堂团队，在最大限度地利用紧凑型硅资源的最佳对齐方面确实取得了很酷的结果PAR！
有关确切的运行时性能的记录，（参考自我记录的表格），或者不要犹豫访问实时 IDE 运行（上面的参考）并自己进行实验。
<SECTION-UNDER-TEST>读者也可能会在小规模实验中认识到外部噪音，因为与 O/S 和托管 IDE 相关的进程会通过不利的 CPU / Lx-CACHE / memIO / process / et al 冲突干预资源使用并影响运行时性能，这一事实排除了这些测量值被用于一些广义解释。
希望所有人都能享受在不断扩大的计算领域所展示的可爱[TIME]结果
[EXPSPACE]
/* ---------------------------------------SETUP-SECTION-UNDER-TEST--*/ use Time;
/* ---------------------------------------SETUP-SECTION-UNDER-TEST--*/ var aStopWATCH_SEQ: Timer;
/* ---------------------------------------SETUP-SECTION-UNDER-TEST--*/ var aStopWATCH_PAR: Timer;
//nst max_idx = 123456; // seems to be too fat for <TiO>-IDE to allocate <TiO>-- /wrappers/chapel: line 6: 24467 Killed
const max_idx = 4096;
//nst max_idx = 8192; // seems to be too long for <TiO>-IDE to let it run [SEQ] part <TiO>-- The request exceeded the 60 second time limit and was terminated
//nst max_idx = 16384; // seems to be too long for <TiO>-IDE to let it run [PAR] part too <TiO>-- /wrappers/chapel: line 6: 12043 Killed
const indices = 1..max_idx;
const adom = {indices, indices};
var A: [adom] int;
[(i,j) in adom] A[i, j] = i*j; // Populate A[,]
var rowsums: [indices] int;
/* ---------------------------------------------SECTION-UNDER-TEST--*/ aStopWATCH_SEQ.start();
for i in indices { // SECTION-UNDER-TEST--
rowsums[i] = + reduce(A[i, ..]); // SECTION-UNDER-TEST--
} // SECTION-UNDER-TEST--
/* ---------------------------------------------SECTION-UNDER-TEST--*/ aStopWATCH_SEQ.stop();
/*
<SECTION-UNDER-TEST> took 8973 [us] to run in [SEQ] mode for 2 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 28611 [us] to run in [SEQ] mode for 4 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 58824 [us] to run in [SEQ] mode for 8 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 486786 [us] to run in [SEQ] mode for 64 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 1019990 [us] to run in [SEQ] mode for 128 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 2010680 [us] to run in [SEQ] mode for 256 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 4154970 [us] to run in [SEQ] mode for 512 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 8260960 [us] to run in [SEQ] mode for 1024 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 15853000 [us] to run in [SEQ] mode for 2048 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 33126800 [us] to run in [SEQ] mode for 4096 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took n/a [us] to run in [SEQ] mode for 8192 elements on <TiO>-IDE
============================================ */
/* ---------------------------------------------SECTION-UNDER-TEST--*/ aStopWATCH_PAR.start();
forall i in indices { // SECTION-UNDER-TEST--
rowsums[i] = + reduce(A[i, ..]); // SECTION-UNDER-TEST--
} // SECTION-UNDER-TEST--
/* ---------------------------------------------SECTION-UNDER-TEST--*/ aStopWATCH_PAR.stop();
/*
<SECTION-UNDER-TEST> took 12131 [us] to run in [PAR] mode for 2 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 8095 [us] to run in [PAR] mode for 4 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 8023 [us] to run in [PAR] mode for 8 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 8156 [us] to run in [PAR] mode for 64 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 7990 [us] to run in [PAR] mode for 128 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 8692 [us] to run in [PAR] mode for 256 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 15134 [us] to run in [PAR] mode for 512 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 16926 [us] to run in [PAR] mode for 1024 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 30671 [us] to run in [PAR] mode for 2048 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 105323 [us] to run in [PAR] mode for 4096 elements on <TiO>-IDE
<SECTION-UNDER-TEST> took 292232 [us] to run in [PAR] mode for 8192 elements on <TiO>-IDE
============================================ */
writeln( rowsums,
"\n <SECTION-UNDER-TEST> took ", aStopWATCH_SEQ.elapsed( Time.TimeUnits.microseconds ), " [us] to run in [SEQ] mode for ", max_idx, " elements on <TiO>-IDE",
"\n <SECTION-UNDER-TEST> took ", aStopWATCH_PAR.elapsed( Time.TimeUnits.microseconds ), " [us] to run in [PAR] mode for ", max_idx, " elements on <TiO>-IDE"
);
这就是使教堂如此伟大的原因
感谢您为 HPC 开发和改进如此出色的计算工具。
于 2017-08-17T05:54:18.283 回答