[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v3 0/9] Improve buffer_is_zero
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH v3 0/9] Improve buffer_is_zero |
Date: |
Mon, 29 Aug 2016 11:46:11 -0700 |
Changes from v2 to v3:
* Unit testing. This includes having x86 attempt all versions of
the accelerator that will run on the hardware. Thus an avx2 host
will run the basic test 5 times (1.5sec on my laptop).
* Drop the ppc and aarch64 specializations. I have improved the
basic integer version to the point that those vectorized versions
are not a win.
In the case of my aarch64 mustang, the integer version is 4 times
faster than the neon version that I delete. With effort I was
able to rewrite the neon version to come to within a factor of 1.1,
but it remained slower than the integer. To be fair, gcc6 makes
very good use of ldp, so the integer path is *also* loading 16 bytes
per insn.
I can forward my standalone aarch64 benchmark if anyone is interested.
Note however that at least the avx2 acceleration is still very much
a win, being about 3 times faster on my laptop. Of course, it's
handling 4 times as much data per loop as the integer version, so
one can still see the overhead caused by using vector insns.
For grins I wrote an avx512 version, if someone has a skylake upon
which to test and benchmark. That requires additional configure
checks, so I didn't bother to include it here.
r~
Richard Henderson (9):
cutils: Move buffer_is_zero and subroutines to a new file
cutils: Remove SPLAT macro
cutils: Export only buffer_is_zero
cutils: Rearrange buffer_is_zero acceleration
cutils: Add test for buffer_is_zero
cutils: Add generic prefetch
cutils: Rewrite x86 buffer zero checking
cutils: Remove aarch64 buffer zero checking
cutils: Remove ppc buffer zero checking
configure | 21 +--
include/qemu/cutils.h | 3 +-
migration/ram.c | 2 +-
migration/rdma.c | 5 +-
tests/Makefile.include | 3 +
tests/test-bufferiszero.c | 78 +++++++++++
util/Makefile.objs | 1 +
util/bufferiszero.c | 332 ++++++++++++++++++++++++++++++++++++++++++++++
util/cutils.c | 244 ----------------------------------
9 files changed, 423 insertions(+), 266 deletions(-)
create mode 100644 tests/test-bufferiszero.c
create mode 100644 util/bufferiszero.c
--
2.7.4
- [Qemu-devel] [PATCH v3 0/9] Improve buffer_is_zero,
Richard Henderson <=
- [Qemu-devel] [PATCH v3 3/9] cutils: Export only buffer_is_zero, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 1/9] cutils: Move buffer_is_zero and subroutines to a new file, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 4/9] cutils: Rearrange buffer_is_zero acceleration, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 9/9] cutils: Remove ppc buffer zero checking, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 8/9] cutils: Remove aarch64 buffer zero checking, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 6/9] cutils: Add generic prefetch, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 5/9] cutils: Add test for buffer_is_zero, Richard Henderson, 2016/08/29
- [Qemu-devel] [PATCH v3 7/9] cutils: Rewrite x86 buffer zero checking, Richard Henderson, 2016/08/29
- Re: [Qemu-devel] [PATCH v3 0/9] Improve buffer_is_zero, Paolo Bonzini, 2016/08/30