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lib/raid6/altivec: Add vpermxor implementation for raid6 Q syndrome

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This patch uses the vpermxor instruction to optimise the raid6 Q
syndrome. This instruction was made available with POWER8, ISA version
2.07. It allows for both vperm and vxor instructions to be done in a
single instruction. This has been tested for correctness on a ppc64le
vm with a basic RAID6 setup containing 5 drives.

The performance benchmarks are from the raid6test in the
/lib/raid6/test directory. These results are from an IBM Firestone
machine with ppc64le architecture. The benchmark results show a 35%
speed increase over the best existing algorithm for powerpc (altivec).
The raid6test has also been run on a big-endian ppc64 vm to ensure it
also works for big-endian architectures.

Performance benchmarks:
  raid6: altivecx4 gen() 18773 MB/s
  raid6: altivecx8 gen() 19438 MB/s

  raid6: vpermxor4 gen() 25112 MB/s
  raid6: vpermxor8 gen() 26279 MB/s

Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
[mpe: Add VPERMXOR macro so we can build with old binutils]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Matt Brown
2017-08-04 13:42:32 +10:00
committed by Michael Ellerman
parent 7004263bd4
commit 751ba79cc5
7 changed files with 161 additions and 3 deletions
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17
lib/raid6/test/Makefile
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@@ -48,7 +48,8 @@ else
gcc -c -x c - >&/dev/null && \
rm ./-.o && echo yes)
ifeq ($(HAS_ALTIVEC),yes)
OBJS += altivec1.o altivec2.o altivec4.o altivec8.o
OBJS += altivec1.o altivec2.o altivec4.o altivec8.o \
vpermxor1.o vpermxor2.o vpermxor4.o vpermxor8.o
endif
endif
ifeq ($(ARCH),tilegx)
@@ -98,6 +99,18 @@ altivec4.c: altivec.uc ../unroll.awk
altivec8.c: altivec.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=8 < altivec.uc > $@
vpermxor1.c: vpermxor.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=1 < vpermxor.uc > $@
vpermxor2.c: vpermxor.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=2 < vpermxor.uc > $@
vpermxor4.c: vpermxor.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=4 < vpermxor.uc > $@
vpermxor8.c: vpermxor.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=8 < vpermxor.uc > $@
int1.c: int.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=1 < int.uc > $@
@@ -123,7 +136,7 @@ tables.c: mktables
./mktables > tables.c
clean:
rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c neon*.c tables.c raid6test
rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c vpermxor*.c neon*.c tables.c raid6test
rm -f tilegx*.c
spotless: clean