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mikmart/matsums.R

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Efficiency of rowSums() vs colSums() in the R C API
Raw
matsums.asm
matsums.o: file format pe-x86-64
Disassembly of section .text:
0000000000000000 <C_rowSums>:
0: 41 54 push r12
2: 55 push rbp
3: 57 push rdi
4: 56 push rsi
5: 53 push rbx
6: 48 83 ec 20 sub rsp,0x20
a: 48 8b 05 00 00 00 00 mov rax,QWORD PTR [rip+0x0] # 11 <C_rowSums+0x11>
11: 49 89 cc mov r12,rcx
14: 48 8b 10 mov rdx,QWORD PTR [rax]
17: e8 00 00 00 00 call 1c <C_rowSums+0x1c>
1c: 48 89 c1 mov rcx,rax
1f: e8 00 00 00 00 call 24 <C_rowSums+0x24>
24: 48 89 c1 mov rcx,rax
27: 48 89 c3 mov rbx,rax
2a: e8 00 00 00 00 call 2f <C_rowSums+0x2f>
2f: 48 63 30 movsxd rsi,DWORD PTR [rax]
32: 48 89 d9 mov rcx,rbx
35: e8 00 00 00 00 call 3a <C_rowSums+0x3a>
3a: b9 01 00 00 00 mov ecx,0x1
3f: 48 63 78 04 movsxd rdi,DWORD PTR [rax+0x4]
43: e8 00 00 00 00 call 48 <C_rowSums+0x48>
48: 48 89 f2 mov rdx,rsi
4b: b9 0e 00 00 00 mov ecx,0xe
50: e8 00 00 00 00 call 55 <C_rowSums+0x55>
55: 48 89 c1 mov rcx,rax
58: e8 00 00 00 00 call 5d <C_rowSums+0x5d>
5d: 48 89 c1 mov rcx,rax
60: 48 89 c5 mov rbp,rax
63: e8 00 00 00 00 call 68 <C_rowSums+0x68>
68: 4c 89 e1 mov rcx,r12
6b: 48 89 c3 mov rbx,rax
6e: e8 00 00 00 00 call 73 <C_rowSums+0x73>
73: 45 31 c0 xor r8d,r8d
76: 48 85 f6 test rsi,rsi
79: 48 89 c2 mov rdx,rax
7c: 7e 13 jle 91 <C_rowSums+0x91>
7e: 66 90 xchg ax,ax
80: 4a c7 04 c3 00 00 00 mov QWORD PTR [rbx+r8*8],0x0
87: 00
88: 49 83 c0 01 add r8,0x1
8c: 4c 39 c6 cmp rsi,r8
8f: 75 ef jne 80 <C_rowSums+0x80>
91: 45 31 c9 xor r9d,r9d
94: 48 85 ff test rdi,rdi
97: 48 8d 04 f5 00 00 00 lea rax,[rsi*8+0x0]
9e: 00
9f: 7e 36 jle d7 <C_rowSums+0xd7>
a1: 45 31 c0 xor r8d,r8d
a4: 48 85 f6 test rsi,rsi
a7: 7e 25 jle ce <C_rowSums+0xce>
a9: 0f 1f 80 00 00 00 00 nop DWORD PTR [rax+0x0]
b0: f2 42 0f 10 04 c3 movsd xmm0,QWORD PTR [rbx+r8*8]
b6: f2 42 0f 58 04 c2 addsd xmm0,QWORD PTR [rdx+r8*8]
bc: f2 42 0f 11 04 c3 movsd QWORD PTR [rbx+r8*8],xmm0
c2: 49 83 c0 01 add r8,0x1
c6: 4c 39 c6 cmp rsi,r8
c9: 75 e5 jne b0 <C_rowSums+0xb0>
cb: 48 01 c2 add rdx,rax
ce: 49 83 c1 01 add r9,0x1
d2: 4c 39 cf cmp rdi,r9
d5: 75 ca jne a1 <C_rowSums+0xa1>
d7: b9 01 00 00 00 mov ecx,0x1
dc: e8 00 00 00 00 call e1 <C_rowSums+0xe1>
e1: 48 89 e8 mov rax,rbp
e4: 48 83 c4 20 add rsp,0x20
e8: 5b pop rbx
e9: 5e pop rsi
ea: 5f pop rdi
eb: 5d pop rbp
ec: 41 5c pop r12
ee: c3 ret
ef: 90 nop
00000000000000f0 <C_colSums>:
f0: 41 54 push r12
f2: 55 push rbp
f3: 57 push rdi
f4: 56 push rsi
f5: 53 push rbx
f6: 48 83 ec 20 sub rsp,0x20
fa: 48 8b 05 00 00 00 00 mov rax,QWORD PTR [rip+0x0] # 101 <C_colSums+0x11>
101: 49 89 cc mov r12,rcx
104: 48 8b 10 mov rdx,QWORD PTR [rax]
107: e8 00 00 00 00 call 10c <C_colSums+0x1c>
10c: 48 89 c1 mov rcx,rax
10f: e8 00 00 00 00 call 114 <C_colSums+0x24>
114: 48 89 c6 mov rsi,rax
117: 48 89 c1 mov rcx,rax
11a: e8 00 00 00 00 call 11f <C_colSums+0x2f>
11f: 48 89 f1 mov rcx,rsi
122: 48 63 18 movsxd rbx,DWORD PTR [rax]
125: e8 00 00 00 00 call 12a <C_colSums+0x3a>
12a: 48 63 70 04 movsxd rsi,DWORD PTR [rax+0x4]
12e: b9 01 00 00 00 mov ecx,0x1
133: e8 00 00 00 00 call 138 <C_colSums+0x48>
138: b9 0e 00 00 00 mov ecx,0xe
13d: 48 89 f2 mov rdx,rsi
140: e8 00 00 00 00 call 145 <C_colSums+0x55>
145: 48 89 c1 mov rcx,rax
148: e8 00 00 00 00 call 14d <C_colSums+0x5d>
14d: 48 89 c1 mov rcx,rax
150: 48 89 c5 mov rbp,rax
153: e8 00 00 00 00 call 158 <C_colSums+0x68>
158: 4c 89 e1 mov rcx,r12
15b: 48 89 c7 mov rdi,rax
15e: e8 00 00 00 00 call 163 <C_colSums+0x73>
163: 48 85 f6 test rsi,rsi
166: 49 89 c1 mov r9,rax
169: 7e 56 jle 1c1 <C_colSums+0xd1>
16b: 45 31 c0 xor r8d,r8d
16e: 66 90 xchg ax,ax
170: 4a c7 04 c7 00 00 00 mov QWORD PTR [rdi+r8*8],0x0
177: 00
178: 49 83 c0 01 add r8,0x1
17c: 4c 39 c6 cmp rsi,r8
17f: 75 ef jne 170 <C_colSums+0x80>
181: 66 0f ef c9 pxor xmm1,xmm1
185: 48 8d 04 dd 00 00 00 lea rax,[rbx*8+0x0]
18c: 00
18d: 45 31 d2 xor r10d,r10d
190: 45 31 c0 xor r8d,r8d
193: 48 85 db test rbx,rbx
196: 66 0f 28 c1 movapd xmm0,xmm1
19a: 7e 16 jle 1b2 <C_colSums+0xc2>
19c: 0f 1f 40 00 nop DWORD PTR [rax+0x0]
1a0: f2 43 0f 58 04 c1 addsd xmm0,QWORD PTR [r9+r8*8]
1a6: 49 83 c0 01 add r8,0x1
1aa: 4c 39 c3 cmp rbx,r8
1ad: 75 f1 jne 1a0 <C_colSums+0xb0>
1af: 49 01 c1 add r9,rax
1b2: f2 42 0f 11 04 d7 movsd QWORD PTR [rdi+r10*8],xmm0
1b8: 49 83 c2 01 add r10,0x1
1bc: 4c 39 d6 cmp rsi,r10
1bf: 75 cf jne 190 <C_colSums+0xa0>
1c1: b9 01 00 00 00 mov ecx,0x1
1c6: e8 00 00 00 00 call 1cb <C_colSums+0xdb>
1cb: 48 89 e8 mov rax,rbp
1ce: 48 83 c4 20 add rsp,0x20
1d2: 5b pop rbx
1d3: 5e pop rsi
1d4: 5f pop rdi
1d5: 5d pop rbp
1d6: 41 5c pop r12
1d8: c3 ret
1d9: 90 nop
1da: 90 nop
1db: 90 nop
1dc: 90 nop
1dd: 90 nop
1de: 90 nop
1df: 90 nop
Raw
matsums.bat
R CMD SHLIB matsums.c
objdump -d -M intel -S matsums.o > matsums.asm
Raw
matsums.c
#include <Rinternals.h>
SEXP C_rowSums(SEXP x) {
SEXP dim = PROTECT(Rf_getAttrib(x, R_DimSymbol));
R_xlen_t n = INTEGER(dim)[0];
R_xlen_t p = INTEGER(dim)[1];
UNPROTECT(1);
SEXP ans = PROTECT(Rf_allocVector(REALSXP, n));
double *ap = REAL(ans), *xp = REAL(x);
for (R_xlen_t i = 0; i < n; i++)
ap[i] = 0.0;
for (R_xlen_t j = 0; j < p; j++) {
for (R_xlen_t i = 0; i < n; i++) {
ap[i] += *xp++;
}
}
UNPROTECT(1);
return ans;
}
SEXP C_colSums(SEXP x) {
SEXP dim = PROTECT(Rf_getAttrib(x, R_DimSymbol));
R_xlen_t n = INTEGER(dim)[0];
R_xlen_t p = INTEGER(dim)[1];
UNPROTECT(1);
SEXP ans = PROTECT(Rf_allocVector(REALSXP, p));
double *ap = REAL(ans), *xp = REAL(x);
for (R_xlen_t j = 0; j < p; j++)
ap[j] = 0.0; // just for similarity with rowSums
for (R_xlen_t j = 0; j < p; j++) {
double sum = 0.0; // R impl. uses long double
for (R_xlen_t i = 0; i < n; i++) {
sum += *xp++;
}
ap[j] = sum;
}
UNPROTECT(1);
return ans;
}
Raw
matsums.R
library(microbenchmark)
C_colSums <- function(x) .Call("C_colSums", x)
C_rowSums <- function(x) .Call("C_rowSums", x)
set.seed(1234)
x <- tcrossprod(rnorm(5000))
dyn.load("matsums.dll")
microbenchmark(
colSums(x),
C_colSums(x),
rowSums(x),
C_rowSums(x)
)
#> Unit: milliseconds
#> expr min lq mean median uq max neval
#> colSums(x) 23.70049 24.81208 25.41287 25.15936 25.82541 31.06992 100
#> C_colSums(x) 31.44613 32.65331 33.33408 33.02726 33.73659 36.64243 100
#> rowSums(x) 49.14745 52.80385 54.28015 54.14990 55.54067 62.06231 100
#> C_rowSums(x) 18.78563 19.49311 20.13990 19.88757 20.44019 25.71116 100
dyn.unload("matsums.dll")
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