我想使用PAPI库来计算缓存缺失。由于我的硬件上没有可用的缓存命中性能计数器，因此我正在尝试确定没有缓存缺失的缓存命中。我正在尝试一些事情。我的代码的第一个版本如下：
int numEvents = 2;
long long values[2];
int events[2] = {PAPI_L1_DCM, PAPI_L2_TCM};
if (PAPI_start_counters(events, numEvents) != PAPI_OK ) // !=PAPI_OK
printf("PAPI error: %d\n", 1);
for(int i=0; i < arr_size; i++)
{
array[i].value = 1;
}
_mm_mfence();
if ((ret1 = PAPI_read_counters(values, numEvents)) != PAPI_OK) {
fprintf(stderr, "PAPI failed to read counters: %s\n", PAPI_strerror(ret1));
exit(1);
}
miss1 = values[0];
_mm_mfence();
for(int i=0; i < arr_size; i++){
array[i].value = array[i].value + 9; // (int) sum
}
_mm_mfence();
if ((ret2 = PAPI_read_counters(values, numEvents)) != PAPI_OK) {
fprintf(stderr, "PAPI failed to read counters: %s\n", PAPI_strerror(ret2));
exit(1);
}
miss2 = values[0];
printf("before flush miss_1 %lli, miss_2 %lli \n", miss1, miss2);
问题在于这段代码应该给我提供缓存命中率，因此L1缓存未命中应该非常低。但是我得到了意外高的miss_2结果。当数组大小为200时，miss_2接近100。由于高数量的缓存未命中，它不会提供任何有效的结果来判断它是否真正被命中。
我也尝试像这样重写它：
if (PAPI_start_counters(events, numEvents) != PAPI_OK ) // !=PAPI_OK
printf("PAPI error: %d\n", 1);
for(int i=0; i < arr_size; i++){
array[i].value = array[i].value + 9; // (int) sum
}
if ( PAPI_stop_counters(values, numEvents) != PAPI_OK)
printf("PAPI error: 2\n");
printf("before flush miss %lli\n", values[0]);
但是这样做的结果更糟，miss_2超过了200。我做错了什么吗？它本应该给出更精确的结果，但现在表现很差。或者我漏了什么。
我已经尝试过去掉围栏，并确信至少它们不会造成任何伤害。我真的很感激任何建议。
PAPI_read_counters 的缺点是它的开销和性能不太好，但现在我不关心性能，我想正确确定缓存命中率。
虽然我也想使用 RDMPC，但我没有找到一个示例可以在不覆盖 _asm 函数的情况下使用它。这真的是使用 rdpmc 的唯一方法吗？不存在已经定义好的函数，我不需要覆盖吗？
编辑： 添加了 PAPI_read 的编译器代码。
./prog6: file format elf64-x86-64
Disassembly of section .init:
00000000000009c0 <_init>:
9c0: 48 83 ec 08 sub $0x8,%rsp
9c4: 48 8b 05 1d 16 20 00 mov 0x20161d(%rip),%rax # 201fe8 <__gmon_start__>
9cb: 48 85 c0 test %rax,%rax
9ce: 74 02 je 9d2 <_init+0x12>
9d0: ff d0 callq *%rax
9d2: 48 83 c4 08 add $0x8,%rsp
9d6: c3 retq
Disassembly of section .plt:
00000000000009e0 <.plt>:
9e0: ff 35 6a 15 20 00 pushq 0x20156a(%rip) # 201f50 <_GLOBAL_OFFSET_TABLE_+0x8>
9e6: ff 25 6c 15 20 00 jmpq *0x20156c(%rip) # 201f58 <_GLOBAL_OFFSET_TABLE_+0x10>
9ec: 0f 1f 40 00 nopl 0x0(%rax)
00000000000009f0 <puts@plt>:
9f0: ff 25 6a 15 20 00 jmpq *0x20156a(%rip) # 201f60 <puts@GLIBC_2.2.5>
9f6: 68 00 00 00 00 pushq $0x0
9fb: e9 e0 ff ff ff jmpq 9e0 <.plt>
0000000000000a00 <clock_gettime@plt>:
a00: ff 25 62 15 20 00 jmpq *0x201562(%rip) # 201f68 <clock_gettime@GLIBC_2.17>
a06: 68 01 00 00 00 pushq $0x1
a0b: e9 d0 ff ff ff jmpq 9e0 <.plt>
0000000000000a10 <getpid@plt>:
a10: ff 25 5a 15 20 00 jmpq *0x20155a(%rip) # 201f70 <getpid@GLIBC_2.2.5>
a16: 68 02 00 00 00 pushq $0x2
a1b: e9 c0 ff ff ff jmpq 9e0 <.plt>
0000000000000a20 <__stack_chk_fail@plt>:
a20: ff 25 52 15 20 00 jmpq *0x201552(%rip) # 201f78 <__stack_chk_fail@GLIBC_2.4>
a26: 68 03 00 00 00 pushq $0x3
a2b: e9 b0 ff ff ff jmpq 9e0 <.plt>
0000000000000a30 <PAPI_read_counters@plt>:
a30: ff 25 4a 15 20 00 jmpq *0x20154a(%rip) # 201f80 <PAPI_read_counters>
a36: 68 04 00 00 00 pushq $0x4
a3b: e9 a0 ff ff ff jmpq 9e0 <.plt>
0000000000000a40 <sched_setaffinity@plt>:
a40: ff 25 42 15 20 00 jmpq *0x201542(%rip) # 201f88 <sched_setaffinity@GLIBC_2.3.4>
a46: 68 05 00 00 00 pushq $0x5
a4b: e9 90 ff ff ff jmpq 9e0 <.plt>
0000000000000a50 <PAPI_start_counters@plt>:
a50: ff 25 3a 15 20 00 jmpq *0x20153a(%rip) # 201f90 <PAPI_start_counters>
a56: 68 06 00 00 00 pushq $0x6
a5b: e9 80 ff ff ff jmpq 9e0 <.plt>
0000000000000a60 <PAPI_stop_counters@plt>:
a60: ff 25 32 15 20 00 jmpq *0x201532(%rip) # 201f98 <PAPI_stop_counters>
a66: 68 07 00 00 00 pushq $0x7
a6b: e9 70 ff ff ff jmpq 9e0 <.plt>
0000000000000a70 <malloc@plt>:
a70: ff 25 2a 15 20 00 jmpq *0x20152a(%rip) # 201fa0 <malloc@GLIBC_2.2.5>
a76: 68 08 00 00 00 pushq $0x8
a7b: e9 60 ff ff ff jmpq 9e0 <.plt>
0000000000000a80 <PAPI_strerror@plt>:
a80: ff 25 22 15 20 00 jmpq *0x201522(%rip) # 201fa8 <PAPI_strerror>
a86: 68 09 00 00 00 pushq $0x9
a8b: e9 50 ff ff ff jmpq 9e0 <.plt>
0000000000000a90 <__printf_chk@plt>:
a90: ff 25 1a 15 20 00 jmpq *0x20151a(%rip) # 201fb0 <__printf_chk@GLIBC_2.3.4>
a96: 68 0a 00 00 00 pushq $0xa
a9b: e9 40 ff ff ff jmpq 9e0 <.plt>
0000000000000aa0 <getrusage@plt>:
aa0: ff 25 12 15 20 00 jmpq *0x201512(%rip) # 201fb8 <getrusage@GLIBC_2.2.5>
aa6: 68 0b 00 00 00 pushq $0xb
aab: e9 30 ff ff ff jmpq 9e0 <.plt>
0000000000000ab0 <exit@plt>:
ab0: ff 25 0a 15 20 00 jmpq *0x20150a(%rip) # 201fc0 <exit@GLIBC_2.2.5>
ab6: 68 0c 00 00 00 pushq $0xc
abb: e9 20 ff ff ff jmpq 9e0 <.plt>
0000000000000ac0 <fwrite@plt>:
ac0: ff 25 02 15 20 00 jmpq *0x201502(%rip) # 201fc8 <fwrite@GLIBC_2.2.5>
ac6: 68 0d 00 00 00 pushq $0xd
acb: e9 10 ff ff ff jmpq 9e0 <.plt>
0000000000000ad0 <__fprintf_chk@plt>:
ad0: ff 25 fa 14 20 00 jmpq *0x2014fa(%rip) # 201fd0 <__fprintf_chk@GLIBC_2.3.4>
ad6: 68 0e 00 00 00 pushq $0xe
adb: e9 00 ff ff ff jmpq 9e0 <.plt>
Disassembly of section .plt.got:
0000000000000ae0 <__cxa_finalize@plt>:
ae0: ff 25 12 15 20 00 jmpq *0x201512(%rip) # 201ff8 <__cxa_finalize@GLIBC_2.2.5>
ae6: 66 90 xchg %ax,%ax
Disassembly of section .text:
0000000000000af0 <main>:
af0: 41 57 push %r15
af2: b9 0f 00 00 00 mov $0xf,%ecx
af7: 41 56 push %r14
af9: 41 55 push %r13
afb: 41 54 push %r12
afd: 55 push %rbp
afe: 53 push %rbx
aff: 48 81 ec 78 01 00 00 sub $0x178,%rsp
b06: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
b0d: 00 00
b0f: 48 89 84 24 68 01 00 mov %rax,0x168(%rsp)
b16: 00
b17: 31 c0 xor %eax,%eax
b19: 48 8d 9c 24 e0 00 00 lea 0xe0(%rsp),%rbx
b20: 00
b21: 48 b8 00 00 00 80 07 movabs $0x8000000780000000,%rax
b28: 00 00 80
b2b: 48 c7 84 24 e0 00 00 movq $0x1,0xe0(%rsp)
b32: 00 01 00 00 00
b37: 48 8d 53 08 lea 0x8(%rbx),%rdx
b3b: 48 89 84 24 c8 00 00 mov %rax,0xc8(%rsp)
b42: 00
b43: 31 c0 xor %eax,%eax
b45: 48 89 d7 mov %rdx,%rdi
b48: f3 48 ab rep stos %rax,%es:(%rdi)
b4b: e8 c0 fe ff ff callq a10 <getpid@plt>
b50: 48 89 da mov %rbx,%rdx
b53: be 80 00 00 00 mov $0x80,%esi
b58: 89 c7 mov %eax,%edi
b5a: e8 e1 fe ff ff callq a40 <sched_setaffinity@plt>
b5f: 85 c0 test %eax,%eax
b61: 0f 85 17 03 00 00 jne e7e <main+0x38e>
b67: 0f ae f0 mfence
b6a: 48 8d 74 24 10 lea 0x10(%rsp),%rsi
b6f: bf 02 00 00 00 mov $0x2,%edi
b74: 0f ae f0 mfence
b77: e8 84 fe ff ff callq a00 <clock_gettime@plt>
b7c: 0f 31 rdtsc
b7e: bf 00 fa 00 00 mov $0xfa00,%edi
b83: 0f ae f0 mfence
b86: 48 c1 e2 20 shl $0x20,%rdx
b8a: 49 89 c6 mov %rax,%r14
b8d: 49 09 d6 or %rdx,%r14
b90: e8 db fe ff ff callq a70 <malloc@plt>
b95: 48 8d bc 24 c8 00 00 lea 0xc8(%rsp),%rdi
b9c: 00
b9d: be 02 00 00 00 mov $0x2,%esi
ba2: 49 89 c4 mov %rax,%r12
ba5: e8 a6 fe ff ff callq a50 <PAPI_start_counters@plt>
baa: 85 c0 test %eax,%eax
bac: 0f 85 88 02 00 00 jne e3a <main+0x34a>
bb2: 4d 89 e7 mov %r12,%r15
bb5: 49 8d 84 24 00 fa 00 lea 0xfa00(%r12),%rax
bbc: 00
bbd: 4c 89 e5 mov %r12,%rbp
bc0: c7 45 00 01 00 00 00 movl $0x1,0x0(%rbp)
bc7: 48 83 c5 40 add $0x40,%rbp
bcb: 48 39 e8 cmp %rbp,%rax
bce: 75 f0 jne bc0 <main+0xd0>
bd0: 4c 8d ac 24 d0 00 00 lea 0xd0(%rsp),%r13
bd7: 00
bd8: be 02 00 00 00 mov $0x2,%esi
bdd: 4c 89 ef mov %r13,%rdi
be0: e8 4b fe ff ff callq a30 <PAPI_read_counters@plt>
be5: 85 c0 test %eax,%eax
be7: 0f 85 b8 02 00 00 jne ea5 <main+0x3b5>
bed: 48 8b 84 24 d0 00 00 mov 0xd0(%rsp),%rax
bf4: 00
bf5: 4c 89 e3 mov %r12,%rbx
bf8: 48 89 44 24 08 mov %rax,0x8(%rsp)
bfd: 0f 1f 00 nopl (%rax)
c00: 83 03 09 addl $0x9,(%rbx)
c03: 48 83 c3 40 add $0x40,%rbx
c07: 48 39 dd cmp %rbx,%rbp
c0a: 75 f4 jne c00 <main+0x110>
c0c: 31 d2 xor %edx,%edx
c0e: 48 8d 35 88 04 00 00 lea 0x488(%rip),%rsi # 109d <_IO_stdin_used+0x2d>
c15: bf 01 00 00 00 mov $0x1,%edi
c1a: 31 c0 xor %eax,%eax
c1c: e8 6f fe ff ff callq a90 <__printf_chk@plt>
c21: be 02 00 00 00 mov $0x2,%esi
c26: 4c 89 ef mov %r13,%rdi
c29: e8 02 fe ff ff callq a30 <PAPI_read_counters@plt>
c2e: 85 c0 test %eax,%eax
c30: 0f 85 6f 02 00 00 jne ea5 <main+0x3b5>
c36: 48 8b 8c 24 d0 00 00 mov 0xd0(%rsp),%rcx
c3d: 00
c3e: 48 8b 54 24 08 mov 0x8(%rsp),%rdx
c43: 48 8d 35 e6 04 00 00 lea 0x4e6(%rip),%rsi # 1130 <_IO_stdin_used+0xc0>
c4a: 31 c0 xor %eax,%eax
c4c: bf 01 00 00 00 mov $0x1,%edi
c51: e8 3a fe ff ff callq a90 <__printf_chk@plt>
c56: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
c5d: 00 00 00
c60: 41 0f ae 3c 24 clflush (%r12)
c65: 49 83 c4 40 add $0x40,%r12
c69: 49 39 dc cmp %rbx,%r12
c6c: 75 f2 jne c60 <main+0x170>
c6e: be 02 00 00 00 mov $0x2,%esi
c73: 4c 89 ef mov %r13,%rdi
c76: e8 b5 fd ff ff callq a30 <PAPI_read_counters@plt>
c7b: 85 c0 test %eax,%eax
c7d: 0f 85 22 02 00 00 jne ea5 <main+0x3b5>
c83: 48 8b ac 24 d0 00 00 mov 0xd0(%rsp),%rbp
c8a: 00
c8b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
c90: 41 83 07 09 addl $0x9,(%r15)
c94: 49 83 c7 40 add $0x40,%r15
c98: 49 39 df cmp %rbx,%r15
c9b: 75 f3 jne c90 <main+0x1a0>
c9d: be 02 00 00 00 mov $0x2,%esi
ca2: 4c 89 ef mov %r13,%rdi
ca5: e8 86 fd ff ff callq a30 <PAPI_read_counters@plt>
caa: 85 c0 test %eax,%eax
cac: 0f 85 f3 01 00 00 jne ea5 <main+0x3b5>
cb2: 48 8b 8c 24 d0 00 00 mov 0xd0(%rsp),%rcx
cb9: 00
cba: 48 8d 35 97 04 00 00 lea 0x497(%rip),%rsi # 1158 <_IO_stdin_used+0xe8>
cc1: bf 01 00 00 00 mov $0x1,%edi
cc6: 31 c0 xor %eax,%eax
cc8: 48 89 ea mov %rbp,%rdx
ccb: e8 c0 fd ff ff callq a90 <__printf_chk@plt>
cd0: be 02 00 00 00 mov $0x2,%esi
cd5: 4c 89 ef mov %r13,%rdi
cd8: e8 83 fd ff ff callq a60 <PAPI_stop_counters@plt>
cdd: 85 c0 test %eax,%eax
cdf: 0f 85 72 01 00 00 jne e57 <main+0x367>
ce5: 0f ae f0 mfence
ce8: 0f 31 rdtsc
cea: bf 02 00 00 00 mov $0x2,%edi
cef: 48 c1 e2 20 shl $0x20,%rdx
cf3: 48 89 c3 mov %rax,%rbx
cf6: 48 8d 74 24 20 lea 0x20(%rsp),%rsi
cfb: 48 09 d3 or %rdx,%rbx
cfe: e8 fd fc ff ff callq a00 <clock_gettime@plt>
d03: bf 01 00 00 00 mov $0x1,%edi
d08: 48 be db 34 b6 d7 82 movabs $0x431bde82d7b634db,%rsi
d0f: de 1b 43
d12: 0f ae f0 mfence
d15: 48 8b 4c 24 20 mov 0x20(%rsp),%rcx
d1a: 48 2b 4c 24 10 sub 0x10(%rsp),%rcx
d1f: 48 69 c9 00 ca 9a 3b imul $0x3b9aca00,%rcx,%rcx
d26: 48 03 4c 24 28 add 0x28(%rsp),%rcx
d2b: 48 2b 4c 24 18 sub 0x18(%rsp),%rcx
d30: 48 89 c8 mov %rcx,%rax
d33: 48 c1 f9 3f sar $0x3f,%rcx
d37: 48 f7 ee imul %rsi
d3a: 48 8d 35 3f 04 00 00 lea 0x43f(%rip),%rsi # 1180 <_IO_stdin_used+0x110>
d41: 31 c0 xor %eax,%eax
d43: 48 c1 fa 12 sar $0x12,%rdx
d47: 48 29 ca sub %rcx,%rdx
d4a: e8 41 fd ff ff callq a90 <__printf_chk@plt>
d4f: 48 89 da mov %rbx,%rdx
d52: bf 01 00 00 00 mov $0x1,%edi
d57: 31 c0 xor %eax,%eax
d59: 4c 29 f2 sub %r14,%rdx
d5c: 48 8d 35 53 03 00 00 lea 0x353(%rip),%rsi # 10b6 <_IO_stdin_used+0x46>
d63: e8 28 fd ff ff callq a90 <__printf_chk@plt>
d68: 31 d2 xor %edx,%edx
d6a: 48 8d 35 56 03 00 00 lea 0x356(%rip),%rsi # 10c7 <_IO_stdin_used+0x57>
d71: 31 c0 xor %eax,%eax
d73: bf 01 00 00 00 mov $0x1,%edi
d78: e8 13 fd ff ff callq a90 <__printf_chk@plt>
d7d: 31 ff xor %edi,%edi
d7f: 48 8d 74 24 30 lea 0x30(%rsp),%rsi
d84: e8 17 fd ff ff callq aa0 <getrusage@plt>
d89: 83 f8 ff cmp $0xffffffff,%eax
d8c: 0f 84 d6 00 00 00 je e68 <main+0x378>
d92: 48 8b 8c 24 b8 00 00 mov 0xb8(%rsp),%rcx
d99: 00
d9a: 48 8b 94 24 b0 00 00 mov 0xb0(%rsp),%rdx
da1: 00
da2: 48 8d 35 3e 03 00 00 lea 0x33e(%rip),%rsi # 10e7 <_IO_stdin_used+0x77>
da9: 31 c0 xor %eax,%eax
dab: bf 01 00 00 00 mov $0x1,%edi
db0: e8 db fc ff ff callq a90 <__printf_chk@plt>
db5: c5 f9 57 c0 vxorpd %xmm0,%xmm0,%xmm0
db9: bf 01 00 00 00 mov $0x1,%edi
dbe: c5 fb 10 0d 12 04 00 vmovsd 0x412(%rip),%xmm1 # 11d8 <_IO_stdin_used+0x168>
dc5: 00
dc6: 48 69 44 24 30 40 42 imul $0xf4240,0x30(%rsp),%rax
dcd: 0f 00
dcf: 48 03 44 24 38 add 0x38(%rsp),%rax
dd4: 48 8d 35 d5 03 00 00 lea 0x3d5(%rip),%rsi # 11b0 <_IO_stdin_used+0x140>
ddb: c4 e1 fb 2a c0 vcvtsi2sd %rax,%xmm0,%xmm0
de0: 48 69 54 24 40 40 42 imul $0xf4240,0x40(%rsp),%rdx
de7: 0f 00
de9: 48 03 54 24 48 add 0x48(%rsp),%rdx
dee: c5 fb 59 c1 vmulsd %xmm1,%xmm0,%xmm0
df2: c4 e1 fb 2c c0 vcvttsd2si %xmm0,%rax
df7: c5 f9 57 c0 vxorpd %xmm0,%xmm0,%xmm0
dfb: c4 e1 fb 2a c2 vcvtsi2sd %rdx,%xmm0,%xmm0
e00: c5 fb 59 c1 vmulsd %xmm1,%xmm0,%xmm0
e04: c4 e1 fb 2c d0 vcvttsd2si %xmm0,%rdx
e09: 48 01 c2 add %rax,%rdx
e0c: 31 c0 xor %eax,%eax
e0e: e8 7d fc ff ff callq a90 <__printf_chk@plt>
e13: 31 c0 xor %eax,%eax
e15: 48 8b 8c 24 68 01 00 mov 0x168(%rsp),%rcx
e1c: 00
e1d: 64 48 33 0c 25 28 00 xor %fs:0x28,%rcx
e24: 00 00
e26: 75 51 jne e79 <main+0x389>
e28: 48 81 c4 78 01 00 00 add $0x178,%rsp
e2f: 5b pop %rbx
e30: 5d pop %rbp
e31: 41 5c pop %r12
e33: 41 5d pop %r13
e35: 41 5e pop %r14
e37: 41 5f pop %r15
e39: c3 retq
e3a: ba 01 00 00 00 mov $0x1,%edx
e3f: 48 8d 35 47 02 00 00 lea 0x247(%rip),%rsi # 108d <_IO_stdin_used+0x1d>
e46: bf 01 00 00 00 mov $0x1,%edi
e4b: 31 c0 xor %eax,%eax
e4d: e8 3e fc ff ff callq a90 <__printf_chk@plt>
e52: e9 5b fd ff ff jmpq bb2 <main+0xc2>
e57: 48 8d 3d 4a 02 00 00 lea 0x24a(%rip),%rdi # 10a8 <_IO_stdin_used+0x38>
e5e: e8 8d fb ff ff callq 9f0 <puts@plt>
e63: e9 7d fe ff ff jmpq ce5 <main+0x1f5>
e68: 48 8d 3d 62 02 00 00 lea 0x262(%rip),%rdi # 10d1 <_IO_stdin_used+0x61>
e6f: e8 7c fb ff ff callq 9f0 <puts@plt>
e74: e9 19 ff ff ff jmpq d92 <main+0x2a2>
e79: e8 a2 fb ff ff callq a20 <__stack_chk_fail@plt>
e7e: 48 8b 0d 9b 11 20 00 mov 0x20119b(%rip),%rcx # 202020 <stderr@@GLIBC_2.2.5>
e85: ba 18 00 00 00 mov $0x18,%edx
e8a: be 01 00 00 00 mov $0x1,%esi
e8f: 48 8d 3d de 01 00 00 lea 0x1de(%rip),%rdi # 1074 <_IO_stdin_used+0x4>
e96: e8 25 fc ff ff callq ac0 <fwrite@plt>
e9b: bf 01 00 00 00 mov $0x1,%edi
ea0: e8 0b fc ff ff callq ab0 <exit@plt>
ea5: 89 c7 mov %eax,%edi
ea7: e8 d4 fb ff ff callq a80 <PAPI_strerror@plt>
eac: 48 8b 3d 6d 11 20 00 mov 0x20116d(%rip),%rdi # 202020 <stderr@@GLIBC_2.2.5>
eb3: be 01 00 00 00 mov $0x1,%esi
eb8: 48 8d 15 49 02 00 00 lea 0x249(%rip),%rdx # 1108 <_IO_stdin_used+0x98>
ebf: 48 89 c1 mov %rax,%rcx
ec2: 31 c0 xor %eax,%eax
ec4: e8 07 fc ff ff callq ad0 <__fprintf_chk@plt>
ec9: bf 01 00 00 00 mov $0x1,%edi
ece: e8 dd fb ff ff callq ab0 <exit@plt>
ed3: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
eda: 00 00 00
edd: 0f 1f 00 nopl (%rax)
0000000000000ee0 <_start>:
ee0: 31 ed xor %ebp,%ebp
ee2: 49 89 d1 mov %rdx,%r9
ee5: 5e pop %rsi
ee6: 48 89 e2 mov %rsp,%rdx
ee9: 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
eed: 50 push %rax
eee: 54 push %rsp
eef: 4c 8d 05 6a 01 00 00 lea 0x16a(%rip),%r8 # 1060 <__libc_csu_fini>
ef6: 48 8d 0d f3 00 00 00 lea 0xf3(%rip),%rcx # ff0 <__libc_csu_init>
efd: 48 8d 3d ec fb ff ff lea -0x414(%rip),%rdi # af0 <main>
f04: ff 15 d6 10 20 00 callq *0x2010d6(%rip) # 201fe0 <__libc_start_main@GLIBC_2.2.5>
f0a: f4 hlt
f0b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
0000000000000f10 <deregister_tm_clones>:
f10: 48 8d 3d f9 10 20 00 lea 0x2010f9(%rip),%rdi # 202010 <__TMC_END__>
f17: 55 push %rbp
f18: 48 8d 05 f1 10 20 00 lea 0x2010f1(%rip),%rax # 202010 <__TMC_END__>
f1f: 48 39 f8 cmp %rdi,%rax
f22: 48 89 e5 mov %rsp,%rbp
f25: 74 19 je f40 <deregister_tm_clones+0x30>
f27: 48 8b 05 aa 10 20 00 mov 0x2010aa(%rip),%rax # 201fd8 <_ITM_deregisterTMCloneTable>
f2e: 48 85 c0 test %rax,%rax
f31: 74 0d je f40 <deregister_tm_clones+0x30>
f33: 5d pop %rbp
f34: ff e0 jmpq *%rax
f36: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
f3d: 00 00 00
f40: 5d pop %rbp
f41: c3 retq
f42: 0f 1f 40 00 nopl 0x0(%rax)
f46: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
f4d: 00 00 00
0000000000000f50 <register_tm_clones>:
f50: 48 8d 3d b9 10 20 00 lea 0x2010b9(%rip),%rdi # 202010 <__TMC_END__>
f57: 48 8d 35 b2 10 20 00 lea 0x2010b2(%rip),%rsi # 202010 <__TMC_END__>
f5e: 55 push %rbp
f5f: 48 29 fe sub %rdi,%rsi
f62: 48 89 e5 mov %rsp,%rbp
f65: 48 c1 fe 03 sar $0x3,%rsi
f69: 48 89 f0 mov %rsi,%rax
f6c: 48 c1 e8 3f shr $0x3f,%rax
f70: 48 01 c6 add %rax,%rsi
f73: 48 d1 fe sar %rsi
f76: 74 18 je f90 <register_tm_clones+0x40>
f78: 48 8b 05 71 10 20 00 mov 0x201071(%rip),%rax # 201ff0 <_ITM_registerTMCloneTable>
f7f: 48 85 c0 test %rax,%rax
f82: 74 0c je f90 <register_tm_clones+0x40>
f84: 5d pop %rbp
f85: ff e0 jmpq *%rax
f87: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
f8e: 00 00
f90: 5d pop %rbp
f91: c3 retq
f92: 0f 1f 40 00 nopl 0x0(%rax)
f96: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
f9d: 00 00 00
0000000000000fa0 <__do_global_dtors_aux>:
fa0: 80 3d 81 10 20 00 00 cmpb $0x0,0x201081(%rip) # 202028 <completed.7696>
fa7: 75 2f jne fd8 <__do_global_dtors_aux+0x38>
fa9: 48 83 3d 47 10 20 00 cmpq $0x0,0x201047(%rip) # 201ff8 <__cxa_finalize@GLIBC_2.2.5>
fb0: 00
fb1: 55 push %rbp
fb2: 48 89 e5 mov %rsp,%rbp
fb5: 74 0c je fc3 <__do_global_dtors_aux+0x23>
fb7: 48 8b 3d 4a 10 20 00 mov 0x20104a(%rip),%rdi # 202008 <__dso_handle>
fbe: e8 1d fb ff ff callq ae0 <__cxa_finalize@plt>
fc3: e8 48 ff ff ff callq f10 <deregister_tm_clones>
fc8: c6 05 59 10 20 00 01 movb $0x1,0x201059(%rip) # 202028 <completed.7696>
fcf: 5d pop %rbp
fd0: c3 retq
fd1: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
fd8: f3 c3 repz retq
fda: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
0000000000000fe0 <frame_dummy>:
fe0: 55 push %rbp
fe1: 48 89 e5 mov %rsp,%rbp
fe4: 5d pop %rbp
fe5: e9 66 ff ff ff jmpq f50 <register_tm_clones>
fea: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
0000000000000ff0 <__libc_csu_init>:
ff0: 41 57 push %r15
ff2: 41 56 push %r14
ff4: 49 89 d7 mov %rdx,%r15
ff7: 41 55 push %r13
ff9: 41 54 push %r12
ffb: 4c 8d 25 36 0d 20 00 lea 0x200d36(%rip),%r12 # 201d38 <__frame_dummy_init_array_entry>
1002: 55 push %rbp
1003: 48 8d 2d 36 0d 20 00 lea 0x200d36(%rip),%rbp # 201d40 <__init_array_end>
100a: 53 push %rbx
100b: 41 89 fd mov %edi,%r13d
100e: 49 89 f6 mov %rsi,%r14
1011: 4c 29 e5 sub %r12,%rbp
1014: 48 83 ec 08 sub $0x8,%rsp
1018: 48 c1 fd 03 sar $0x3,%rbp
101c: e8 9f f9 ff ff callq 9c0 <_init>
1021: 48 85 ed test %rbp,%rbp
1024: 74 20 je 1046 <__libc_csu_init+0x56>
1026: 31 db xor %ebx,%ebx
1028: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
102f: 00
1030: 4c 89 fa mov %r15,%rdx
1033: 4c 89 f6 mov %r14,%rsi
1036: 44 89 ef mov %r13d,%edi
1039: 41 ff 14 dc callq *(%r12,%rbx,8)
103d: 48 83 c3 01 add $0x1,%rbx
1041: 48 39 dd cmp %rbx,%rbp
1044: 75 ea jne 1030 <__libc_csu_init+0x40>
1046: 48 83 c4 08 add $0x8,%rsp
104a: 5b pop %rbx
104b: 5d pop %rbp
104c: 41 5c pop %r12
104e: 41 5d pop %r13
1050: 41 5e pop %r14
1052: 41 5f pop %r15
1054: c3 retq
1055: 90 nop
1056: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
105d: 00 00 00
0000000000001060 <__libc_csu_fini>:
1060: f3 c3 repz retq
Disassembly of section .fini:
0000000000001064 <_fini>:
1064: 48 83 ec 08 sub $0x8,%rsp
1068: 48 83 c4 08 add $0x8,%rsp
106c: c3 retq
我的对象大小为64，并且我已经添加了初始化：
typedef struct _object{
int value;
int pad_0;
int * pad_2;
int * pad_3;
int * pad_4;
int * pad_5;
int * pad_6;
int * pad_7;
int * pad_8;
} object;
object * array;
int arr_size = 1000;
array = (object *) malloc(arr_size * sizeof(object));
for(int i=0; i < arr_size; i++){
array[i].value = 1;
}
asm()覆盖函数”的事情？你不需要自修改代码或任何奇怪的东西，只需要使用普通的GNU C内联汇编。或者使用__builtin_ia32_rdpmc，但是https://software.intel.com/en-us/forums/software-tuning-performance-optimization-platform-monitoring/topic/595214报告称，GCC 5可能不会将其视为易失性并优化两个调用以使用相同的值。显然这仍然是gcc8.2中的一个错误：https://godbolt.org/z/p8c_ND。 - Peter Cordes__rdpmc(int)在GCC 6.5、7.4+和8.3+（以及即将推出的9.0版本）中已经正确地被声明为volatile。https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87550。事实证明，它已经被报告并修复，但只有Godbolt上的GCC trunk是足够新的才能拥有它。 - Peter CordesMEM_LOAD_RETIRED.L1_HIT的计数，如果你只看这个，而不是全部-命中差异。 - Peter Cordes