How many cycles are required to add long ints on a xeon?

from timing trials, it appears that 2 clock ticks are needed.

**/proc/info says**

model name : Intel(R) Xeon(R) CPU X5660 @ 2.80GHz

**sample c code (loop.02.c)**

```
unsigned long i, j=0;
for(i=0; i<(0xFFFFFFFF);i++) j+=3;
```

**assembler code**

```
21:loop.02.c **** for(i=0; i<(0xFFFFFFFF);i++) j+=3;
34 .loc 1 21 0
35 001e 48C745F0 movq $0, -16(%rbp)
35 00000000
36 0026 EB0A jmp .L2
37 .L3:
38 0028 488345F8 addq $3, -8(%rbp)
38 03
39 002d 488345F0 addq $1, -16(%rbp)
39 01
40 .L2:
41 0032 B8FEFFFF movl $4294967294, %eax
41 FF
42 0037 483945F0 cmpq %rax, -16(%rbp)
43 003b 76EB jbe .L3
```

so the loop executes 5 instructions: **addq addq movl cmpq jbe**

the loop iterates 0xFFFFFFFF = 16^8 = 4294967296 = 4G times

/usr/bin/time -f %e ./loop.02

yields 10.78 seconds, almost all of which is in the loop

4G*5 instructions / 10.78 seconds = 1.85G instructions/sec

versus the advertised 2.80GHz cycles/sec

for an average of 2.8/1.8 = 1.6 cycles/instruction

that rate makes sense if, say, 2 of the 5 instructions in the loop take 2 cycles and the others take 1 cycle.

is this the correct interpretation of the timing results?

where is a specification of the number of cycles per instruction?

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