随笔-处理器微架构-测量最大IPC(流水线宽度)

目录

• 固定cpu频率
• max_ipc_test.sh

固定cpu频率

随笔-处理器微架构-固定cpu频率 - LiYanbin - 博客园

max_ipc_test.sh

#!/bin/bash

[[ -z "$1" || -z "$2" ]] && {
    echo "usage: $0 [cpuid] [nop_count]"
    exit
}

cpuid=$1
nop_count=$2

echo 'void main() { do {__asm__ (' > nop.c
for ((i = 1; i <= $nop_count; i++)); do
echo '"nop\n\t"' >> nop.c;
done
echo ');} while(1);}' >> nop.c

gcc -O0 nop.c -o nop

echo $?
[[ $? -ne 0 ]] && exit -1


set -x
[ -f ./nop ] && {
    perf stat -C $cpuid --timeout 2000 taskset -c $cpuid ./nop
}
set +x

rm nop.c
rm nop

$ sudo bash max_ipc_test.sh 7 4
...                
    12,290,206,450      instructions                     #    3.97  insn per cycle 
...

当nop_count较小，可能因为while(1)分支指令达不到max ipc，可以增加nop_count来弱化while(1)分支指令