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From bb3d1b67fd0f42ae00af811c624ea1c44541034d Mon Sep 17 00:00:00 2001
From: Siarhei Siamashka <siarhei.siamashka@nokia.com>
Date: Sun, 6 Mar 2011 16:17:12 +0200
Subject: [PATCH 13/40] ARM: use prefetch in nearest scaled 'src_0565_0565'
Benchmark on ARM Cortex-A8 r1p3 @500MHz, 32-bit LPDDR @166MHz:
Microbenchmark (scaling 2000x2000 image with scale factor close to 1x):
before: op=1, src=10020565, dst=10020565, speed=75.02 MPix/s
after: op=1, src=10020565, dst=10020565, speed=73.63 MPix/s
Benchmark on ARM Cortex-A8 r2p2 @1GHz, 32-bit LPDDR @200MHz:
Microbenchmark (scaling 2000x2000 image with scale factor close to 1x):
before: op=1, src=10020565, dst=10020565, speed=176.12 MPix/s
after: op=1, src=10020565, dst=10020565, speed=267.50 MPix/s
---
pixman/pixman-arm-simd-asm.S | 27 +++++++++++++++++++++++++--
1 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/pixman/pixman-arm-simd-asm.S b/pixman/pixman-arm-simd-asm.S
index 7567700..dd1366d 100644
--- a/pixman/pixman-arm-simd-asm.S
+++ b/pixman/pixman-arm-simd-asm.S
@@ -348,6 +348,7 @@ pixman_asm_function pixman_scaled_nearest_scanline_0565_0565_SRC_asm_armv6
TMP1 .req r4
TMP2 .req r5
VXMASK .req r6
+ PF_OFFS .req r7
ldr UNIT_X, [sp]
push {r4, r5, r6, r7}
@@ -366,12 +367,33 @@ pixman_asm_function pixman_scaled_nearest_scanline_0565_0565_SRC_asm_armv6
strh TMP2, [DST], #2
.endm
+ /*
+ * stop prefetch before reaching the end of scanline (a good behaving
+ * value selected based on some benchmarks with short scanlines)
+ */
+ #define PREFETCH_BRAKING_DISTANCE 32
+
/* now do the scaling */
and TMP1, VXMASK, VX, lsr #15
add VX, VX, UNIT_X
- subs W, #4
+ subs W, #(8 + PREFETCH_BRAKING_DISTANCE)
+ blt 2f
+ /* set prefetch distance to 80 pixels ahead */
+ add PF_OFFS, VX, UNIT_X, lsl #6
+ add PF_OFFS, PF_OFFS, UNIT_X, lsl #4
+1: /* main loop, process 8 pixels per iteration with prefetch */
+ subs W, W, #8
+ add PF_OFFS, UNIT_X, lsl #3
+ scale_2_pixels
+ scale_2_pixels
+ scale_2_pixels
+ scale_2_pixels
+ pld [SRC, PF_OFFS, lsr #15]
+ bge 1b
+2:
+ subs W, #(4 - 8 - PREFETCH_BRAKING_DISTANCE)
blt 2f
-1: /* main loop, process 4 pixels per iteration */
+1: /* process the remaining pixels */
scale_2_pixels
scale_2_pixels
subs W, W, #4
@@ -394,6 +416,7 @@ pixman_asm_function pixman_scaled_nearest_scanline_0565_0565_SRC_asm_armv6
.unreq TMP1
.unreq TMP2
.unreq VXMASK
+ .unreq PF_OFFS
/* return */
pop {r4, r5, r6, r7}
bx lr
--
1.6.6.1
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