[MPlayer-dev-eng] Fwd: [xine-devel] memcpy.c speedup patch

[Arpi]

maybe we should port these changes to fastemmcpy?

--------- Forwarded message ---------
From: Jonathan Brown <jbrown at emergence.uk.net>
To: xine-devel at lists.sourceforge.net
Subject: [xine-devel] memcpy.c speedup patch

I found the same mistake in both sse_memcpy and mmx2_memcpy. They both 
presume that prefetchnta prefetches 64 bytes. In actual fact, the p3 
prefetches 32 bytes and the p4 prefetches 128 bytes. The patch optimizes 
it correctly for the p3. If you want to optimize for the p4 you should 
really use movdqa/movdqu.

Please apply to the tree.

CC any replies to me as I am not on the list.

Here are the results on my machine:


------------------------------------------------------
WITHOUT PATCH
------------------------------------------------------


Run 1	glibc memcpy() : 886602411
	linux kernel memcpy() : 853727718
	MMX optimized memcpy() : 813381025
	MMXEXT optimized memcpy() : 611290441
	SSE optimized memcpy() : 622632865

Run 2	glibc memcpy() : 853194421
	linux kernel memcpy() : 853906195
	MMX optimized memcpy() : 811439122
	MMXEXT optimized memcpy() : 615564847
	SSE optimized memcpy() : 622085572

Run 3	glibc memcpy() : 874273009
	linux kernel memcpy() : 853243982
	MMX optimized memcpy() : 811123010
	MMXEXT optimized memcpy() : 612914732
	SSE optimized memcpy() : 623385322

Run 4	glibc memcpy() : 872962086
	linux kernel memcpy() : 852637064
	MMX optimized memcpy() : 812423490
	MMXEXT optimized memcpy() : 616541095
	SSE optimized memcpy() : 622359380

Run 5	glibc memcpy() : 871590819
	linux kernel memcpy() : 854843246
	MMX optimized memcpy() : 812416964
	MMXEXT optimized memcpy() : 613631746
	SSE optimized memcpy() : 620818979

------------------------------------------------------
WITH  PATCH
------------------------------------------------------

Run 1	glibc memcpy() : 875260935
	linux kernel memcpy() : 855195229
	MMX optimized memcpy() : 815879691
	MMXEXT optimized memcpy() : 510607166
	SSE optimized memcpy() : 515002950

Run 2	glibc memcpy() : 853993138
	linux kernel memcpy() : 855955195
	MMX optimized memcpy() : 811581836
	MMXEXT optimized memcpy() : 527623830
	SSE optimized memcpy() : 512657609

Run 3	glibc memcpy() : 872485301
	linux kernel memcpy() : 851106279
	MMX optimized memcpy() : 811177856
	MMXEXT optimized memcpy() : 509514430
	SSE optimized memcpy() : 517702228

Run 4	glibc memcpy() : 879030747
	linux kernel memcpy() : 856619835
	MMX optimized memcpy() : 817141239
	MMXEXT optimized memcpy() : 512585798
	SSE optimized memcpy() : 515385082

Run 5	glibc memcpy() : 874519760
	linux kernel memcpy() : 853971343
	MMX optimized memcpy() : 813392177
	MMXEXT optimized memcpy() : 508638682
	SSE optimized memcpy() : 514397110


processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 8
model name	: Pentium III (Coppermine)
stepping	: 6
cpu MHz		: 800.067
cache size	: 256 KB
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 2
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov 
pat pse36 mmx fxsr sse
bogomips	: 1585.15



diff -ur xine-lib-1-beta2/src/xine-utils/memcpy.c 
my-xine-lib-1-beta2/src/xine-utils/memcpy.c
--- xine-lib-1-beta2/src/xine-utils/memcpy.c    2002-12-22 
20:48:28.000000000 +0000
+++ my-xine-lib-1-beta2/src/xine-utils/memcpy.c 2003-01-09 
06:11:36.000000000 +0000
@@ -168,10 +168,15 @@
    /* PREFETCH has effect even for MOVSB instruction ;) */
    __asm__ __volatile__ (
      "   prefetchnta (%0)\n"
+    "   prefetchnta 32(%0)\n"
      "   prefetchnta 64(%0)\n"
+    "   prefetchnta 96(%0)\n"
      "   prefetchnta 128(%0)\n"
+    "   prefetchnta 160(%0)\n"
      "   prefetchnta 192(%0)\n"
+    "   prefetchnta 224(%0)\n"
      "   prefetchnta 256(%0)\n"
+    "   prefetchnta 288(%0)\n"
      : : "r" (from) );

    if(len >= MIN_LEN)
@@ -193,6 +198,7 @@
        {
          __asm__ __volatile__ (
          "prefetchnta 320(%0)\n"
+       "prefetchnta 352(%0)\n"
          "movups (%0), %%xmm0\n"
          "movups 16(%0), %%xmm1\n"
          "movups 32(%0), %%xmm2\n"
@@ -215,6 +221,7 @@
        {
          __asm__ __volatile__ (
          "prefetchnta 320(%0)\n"
+       "prefetchnta 352(%0)\n"
          "movaps (%0), %%xmm0\n"
          "movaps 16(%0), %%xmm1\n"
          "movaps 32(%0), %%xmm2\n"
@@ -300,10 +307,15 @@
    /* PREFETCH has effect even for MOVSB instruction ;) */
    __asm__ __volatile__ (
      "   prefetchnta (%0)\n"
+    "   prefetchnta 32(%0)\n"
      "   prefetchnta 64(%0)\n"
+    "   prefetchnta 96(%0)\n"
      "   prefetchnta 128(%0)\n"
+    "   prefetchnta 160(%0)\n"
      "   prefetchnta 192(%0)\n"
+    "   prefetchnta 224(%0)\n"
      "   prefetchnta 256(%0)\n"
+    "   prefetchnta 288(%0)\n"
      : : "r" (from) );

    if(len >= MIN_LEN)
@@ -323,6 +335,7 @@
      {
        __asm__ __volatile__ (
        "prefetchnta 320(%0)\n"
+      "prefetchnta 352(%0)\n"
        "movq (%0), %%mm0\n"
        "movq 8(%0), %%mm1\n"
        "movq 16(%0), %%mm2\n"



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