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[Bug target/53659] New: ARM: Using -mcpu=cortex-a9 option results in bad performance for Cortex-A9 processor in C-Ray phoronix benchmark
- From: "siarhei.siamashka at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 13 Jun 2012 18:56:24 +0000
- Subject: [Bug target/53659] New: ARM: Using -mcpu=cortex-a9 option results in bad performance for Cortex-A9 processor in C-Ray phoronix benchmark
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53659
Bug #: 53659
Summary: ARM: Using -mcpu=cortex-a9 option results in bad
performance for Cortex-A9 processor in C-Ray phoronix
benchmark
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: target
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: siarhei.siamashka@gmail.com
gcc version 4.7.0
--with-arch=armv7-a --with-float=hard --with-fpu=neon --with-mode=thumb
$ cd /tmp
$ wget http://www.phoronix-test-suite.com/benchmark-files/c-ray-1.1.tar.gz
$ tar -xzf c-ray-1.1.tar.gz
$ cd c-ray-1.1
$ make clean && make
gcc -O3 -ffast-math -c -o c-ray-mt.o c-ray-mt.c
gcc -o c-ray-mt c-ray-mt.o -lm -lpthread
$ ./c-ray-mt -t 32 -s 160x120 -r 8 -i sphfract -o output.ppm
c-ray-mt v1.1
Rendering took: 6 seconds (6683 milliseconds)
$ sed -i "s,-O3,-O3 -mcpu=cortex-a9,g" Makefile
$ make clean && make
gcc -O3 -mcpu=cortex-a9 -ffast-math -c -o c-ray-mt.o c-ray-mt.c
gcc -o c-ray-mt c-ray-mt.o -lm -lpthread
$ ./c-ray-mt -t 32 -s 160x120 -r 8 -i sphfract -o output.ppm
c-ray-mt v1.1
Rendering took: 7 seconds (7906 milliseconds)
Comparing to the default -march=armv7-a configuration, -mcpu=cortex-a9 caused a
~18% slowdown (7906 milliseconds vs. 6683 milliseconds). The test was run on a
dual-core ARM Cortex-A9 @1.2GHz