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[2/5] AArch64: Improve A64FX memset for large sizes

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Improve performance of large memsets. Simplify alignment code. For zero memset
use DC ZVA, which almost doubles performance. For non-zero memsets use the
unroll8 loop which is about 10% faster.

Reviewed-by: Naohiro Tamura <naohirot@fujitsu.com>
This commit is contained in:
Wilco Dijkstra 2021-08-10 13:39:37 +01:00
parent 07b427296b
commit 9bc2ed8f46
1 changed files with 25 additions and 60 deletions
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85
sysdeps/aarch64/multiarch/memset_a64fx.S
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@ -27,14 +27,11 @@
*/
#define L1_SIZE (64*1024) // L1 64KB
#define L2_SIZE (8*1024*1024) // L2 8MB - 1MB
#define L2_SIZE (8*1024*1024) // L2 8MB
#define CACHE_LINE_SIZE 256
#define PF_DIST_L1 (CACHE_LINE_SIZE * 16) // Prefetch distance L1
#define ZF_DIST (CACHE_LINE_SIZE * 21) // Zerofill distance
#define rest x8
#define rest x2
#define vector_length x9
#define vl_remainder x10 // vector_length remainder
#define cl_remainder x11 // CACHE_LINE_SIZE remainder
#if HAVE_AARCH64_SVE_ASM
# if IS_IN (libc)
@ -42,14 +39,6 @@
.arch armv8.2-a+sve
.macro dc_zva times
dc zva, tmp1
add tmp1, tmp1, CACHE_LINE_SIZE
.if \times-1
dc_zva "(\times-1)"
.endif
.endm
.macro st1b_unroll first=0, last=7
st1b z0.b, p0, [dst, \first, mul vl]
.if \last-\first
@ -188,54 +177,30 @@ L(L1_prefetch): // if rest >= L1_SIZE
cbnz rest, L(unroll32)
ret
L(L2):
// align dst address at vector_length byte boundary
sub tmp1, vector_length, 1
ands tmp2, dst, tmp1
// if vl_remainder == 0
b.eq 1f
sub vl_remainder, vector_length, tmp2
// process remainder until the first vector_length boundary
whilelt p2.b, xzr, vl_remainder
st1b z0.b, p2, [dst]
add dst, dst, vl_remainder
sub rest, rest, vl_remainder
// align dstin address at CACHE_LINE_SIZE byte boundary
1: mov tmp1, CACHE_LINE_SIZE
ands tmp2, dst, CACHE_LINE_SIZE - 1
// if cl_remainder == 0
b.eq L(L2_dc_zva)
sub cl_remainder, tmp1, tmp2
// process remainder until the first CACHE_LINE_SIZE boundary
mov tmp1, xzr // index
2: whilelt p2.b, tmp1, cl_remainder
st1b z0.b, p2, [dst, tmp1]
incb tmp1
cmp tmp1, cl_remainder
b.lo 2b
add dst, dst, cl_remainder
sub rest, rest, cl_remainder
L(L2_dc_zva):
// zero fill
mov tmp1, dst
dc_zva (ZF_DIST / CACHE_LINE_SIZE) - 1
mov zva_len, ZF_DIST
add tmp1, zva_len, CACHE_LINE_SIZE * 2
// unroll
// count >= L2_SIZE
.p2align 3
1: st1b_unroll 0, 3
add tmp2, dst, zva_len
dc zva, tmp2
st1b_unroll 4, 7
add tmp2, tmp2, CACHE_LINE_SIZE
dc zva, tmp2
add dst, dst, CACHE_LINE_SIZE * 2
sub rest, rest, CACHE_LINE_SIZE * 2
cmp rest, tmp1 // ZF_DIST + CACHE_LINE_SIZE * 2
b.ge 1b
cbnz rest, L(unroll8)
ret
L(L2):
tst valw, 255
b.ne L(unroll8)
// align dst to CACHE_LINE_SIZE byte boundary
and tmp2, dst, CACHE_LINE_SIZE - 1
st1b z0.b, p0, [dst, 0, mul vl]
st1b z0.b, p0, [dst, 1, mul vl]
st1b z0.b, p0, [dst, 2, mul vl]
st1b z0.b, p0, [dst, 3, mul vl]
sub dst, dst, tmp2
add count, count, tmp2
// clear cachelines using DC ZVA
sub count, count, CACHE_LINE_SIZE * 2
.p2align 4
1: add dst, dst, CACHE_LINE_SIZE
dc zva, dst
subs count, count, CACHE_LINE_SIZE
b.hi 1b
add count, count, CACHE_LINE_SIZE
add dst, dst, CACHE_LINE_SIZE
b L(last)
END (MEMSET)
libc_hidden_builtin_def (MEMSET)