ahs
919fb7f2e0
avx2 implementation for memset.
This patch includes handwritten avx2
assembly for memset 64-bit. Uses
non-temporal stores for very large sizes.
Also includes dynamic dispatch for APIs
having multiple implementations.
Convincing benchmark improvements for sizes above 512 bytes, and
although the slight regression for small sizes is unfortunate, it's
probably small enough to be okay?
Before:
BM_string_memset/8/0 3.06 ns 3.04 ns 222703428 bytes_per_second=2.45261G/s
BM_string_memset/16/0 3.50 ns 3.47 ns 202569932 bytes_per_second=4.29686G/s
BM_string_memset/32/0 3.50 ns 3.48 ns 200064955 bytes_per_second=8.57386G/s
BM_string_memset/64/0 3.49 ns 3.46 ns 201928186 bytes_per_second=17.2184G/s
BM_string_memset/512/0 14.8 ns 14.7 ns 47776178 bytes_per_second=32.3887G/s
BM_string_memset/1024/0 27.3 ns 27.1 ns 25884933 bytes_per_second=35.2515G/s
BM_string_memset/8192/0 203 ns 201 ns 3476903 bytes_per_second=37.9311G/s
BM_string_memset/16384/0 402 ns 399 ns 1750471 bytes_per_second=38.2725G/s
BM_string_memset/32768/0 932 ns 925 ns 755750 bytes_per_second=33.0071G/s
BM_string_memset/65536/0 2038 ns 2014 ns 347060 bytes_per_second=30.3057G/s
BM_string_memset/131072/0 4012 ns 3980 ns 175186 bytes_per_second=30.6682G/s
After:
BM_string_memset/8/0 3.32 ns 3.23 ns 208939089 bytes_per_second=2.3051G/s
BM_string_memset/16/0 4.07 ns 3.98 ns 173479615 bytes_per_second=3.74822G/s
BM_string_memset/32/0 4.07 ns 3.95 ns 177208119 bytes_per_second=7.54344G/s
BM_string_memset/64/0 4.09 ns 4.00 ns 174729144 bytes_per_second=14.8878G/s
BM_string_memset/512/0 10.7 ns 10.4 ns 65922763 bytes_per_second=45.6611G/s
BM_string_memset/1024/0 18.0 ns 17.6 ns 40489136 bytes_per_second=54.3166G/s
BM_string_memset/8192/0 109 ns 106 ns 6577711 bytes_per_second=71.7667G/s
BM_string_memset/16384/0 221 ns 210 ns 3343800 bytes_per_second=72.684G/s
BM_string_memset/32768/0 655 ns 623 ns 1153501 bytes_per_second=48.9781G/s
BM_string_memset/65536/0 1547 ns 1495 ns 461702 bytes_per_second=40.8154G/s
BM_string_memset/131072/0 2991 ns 2924 ns 240189 bytes_per_second=41.7438G/s
This patch drops the wmemset() code because we don't even have a
microbenchmark for it, we have as many implementations checked in as we
have non-test call sites (!), so at this point it seems like we've spent
more time maintaining wmemset() than running it!
Test: bionic/tests/run-on-host.sh 64
Signed-off-by: ahs <amrita.h.s@intel.com>
Change-Id: Ie5047df5300638c1e4c69f8285d33d034f79c83b