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From: Max Bruce <max.bruce12@gmail.com>
To: gsl-discuss@sourceware.org
Subject: Reduce cache misses for source_gemm_r
Date: Fri, 19 Oct 2018 03:10:00 -0000	[thread overview]
Message-ID: <CABb0SYR+gNfaui-M6aWg8Ed6cQ8=N8YyBYP+LQgS1VXWG1H-Kg@mail.gmail.com> (raw)

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Hey guys,

I'm new to contributing to GNU projects, but... I'm guessing I send
commits through here? Would appreciate some sort of note on the
procedure on the website

I noticed that your matrix multiplication code had bad cache
performance due to a misordering of a loop. In a replicated version of
my change, I saw about 20% performance gains on my AMD FX CPU.

Do let me know if this is not the correct contribution procedure.

-Max

[-- Attachment #2: 0001-Reduce-cache-misses-for-source_gemm_r.patch --]
[-- Type: text/x-patch, Size: 1622 bytes --]

From 0345eaf2eb48997fa3d00fae2b37cf416d3713d4 Mon Sep 17 00:00:00 2001
From: JavaProphet <max.bruce12@gmail.com>
Date: Thu, 18 Oct 2018 20:00:47 -0700
Subject: [PATCH] Reduce cache misses for source_gemm_r

---
 cblas/source_gemm_r.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/cblas/source_gemm_r.h b/cblas/source_gemm_r.h
index a008d22..7c9848e 100644
--- a/cblas/source_gemm_r.h
+++ b/cblas/source_gemm_r.h
@@ -71,8 +71,8 @@
 
     /* form  C := alpha*A*B + C */
 
-    for (k = 0; k < K; k++) {
-      for (i = 0; i < n1; i++) {
+    for (i = 0; i < n1; i++) {
+      for (k = 0; k < K; k++) {
         const BASE temp = alpha * F[ldf * i + k];
         if (temp != 0.0) {
           for (j = 0; j < n2; j++) {
@@ -86,8 +86,8 @@
 
     /* form  C := alpha*A*B' + C */
 
+  for (j = 0; j < n2; j++) {
     for (i = 0; i < n1; i++) {
-      for (j = 0; j < n2; j++) {
         BASE temp = 0.0;
         for (k = 0; k < K; k++) {
           temp += F[ldf * i + k] * G[ldg * j + k];
@@ -98,8 +98,8 @@
 
   } else if (TransF == CblasTrans && TransG == CblasNoTrans) {
 
+  for (i = 0; i < n1; i++) {
     for (k = 0; k < K; k++) {
-      for (i = 0; i < n1; i++) {
         const BASE temp = alpha * F[ldf * k + i];
         if (temp != 0.0) {
           for (j = 0; j < n2; j++) {
@@ -111,8 +111,8 @@
 
   } else if (TransF == CblasTrans && TransG == CblasTrans) {
 
+  for (j = 0; j < n2; j++) {
     for (i = 0; i < n1; i++) {
-      for (j = 0; j < n2; j++) {
         BASE temp = 0.0;
         for (k = 0; k < K; k++) {
           temp += F[ldf * k + i] * G[ldg * j + k];
-- 
2.7.4


             reply	other threads:[~2018-10-19  3:10 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-19  3:10 Max Bruce [this message]
2018-10-19  8:18 ` Patrick Alken

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