On 27/01/2016 08:33, Liang Li wrote: > buffer_find_nonzero_offset() is a hot function during live migration. > Now it use SSE2 instructions for optimization. For platform supports > AVX2 instructions, use the AVX2 instructions for optimization can help > to improve the performance of zero page checking about 30% comparing > to SSE2. > Live migration can be faster with this optimization, the test result > shows that for an 8GB RAM idle guest, this patch can help to shorten > the total live migration time about 6%. > > This patch use the ifunc mechanism to select the proper function when > running, for platform supports AVX2, execute the AVX2 instructions, > else, execute the original instructions. > > With this patch, the QEMU binary can run on both platforms support AVX2 > or not. > > Compiler which doesn't support the AVX2 and ifunc attribute can also build > the source code successfully. > > v5 -> v4 changes: > * Enhance the ifunc attribute detection (Paolo's suggestion) > > v3 -> v4 changes: > * Use the GCC #pragma to make things simple (Paolo's suggestion) > * Put avx2 related code in cutils.c (Richard's suggestion) > * Change the configure, detect ifunc and avx2 attributes together > > v2 -> v3 changes: > * Detect the ifunc attribute support (Paolo's suggestion) > * Use the ifunc attribute instead of the inline asm (Richard's suggestion) > * Change the configure (Juan's suggestion) > > Liang Li (2): > configure: detect ifunc and avx2 attribute > cutils: add avx2 instruction optimization > > configure | 21 +++++++++ > include/qemu-common.h | 8 +--- > util/cutils.c | 118 > ++++++++++++++++++++++++++++++++++++++++++++++++-- > 3 files changed, 136 insertions(+), 11 deletions(-)
Reviewed-by: Paolo Bonzini <[email protected]>
