与其说是cache实验,不如说这是一个数据结构与算法的课程,因为我还没学,所以先放弃一下,以后再补吧.
把writeup翻译了看一遍:大概就知道要干什么了.
在csim.c编写一个缓存模拟器,达到和csim-ref相同的效果.
如图:
是一个命令行程序,以字符串为输入,可以读取traces中的文件,进行缓存的模拟并返回输出结果.
很明显,csim.c文件输入相应的s,E,b后,会生成对应的缓存.
参考:https://zhuanlan.zhihu.com/p/484657229
/*
* A Cache Simulator by Deconx
* 2022/3/19
*/
#include "cachelab.h"
#include <unistd.h>
#include <getopt.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
typedef struct cache_line
{
int valid; //有效位
int tag; //标记位
int time_tamp; //时间戳
} Cache_line;
typedef struct cache_
{
int S;
int E;
int B;
Cache_line **line;
} Cache;
int hit_count = 0, miss_count = 0, eviction_count = 0; // 记录冲突不命中、缓存不命中
int verbose = 0; //是否打印详细信息
char t[1000];
Cache *cache = NULL;
void Init_Cache(int s, int E, int b)
{
int S = 1 << s;
int B = 1 << b;
cache = (Cache *)malloc(sizeof(Cache));
cache->S = S;
cache->E = E;
cache->B = B;
cache->line = (Cache_line **)malloc(sizeof(Cache_line *) * S);
for (int i = 0; i < S; i++)
{
cache->line[i] = (Cache_line *)malloc(sizeof(Cache_line) * E);
for (int j = 0; j < E; j++)
{
cache->line[i][j].valid = 0; //初始时，高速缓存是空的
cache->line[i][j].tag = -1;
cache->line[i][j].time_tamp = 0;
}
}
}
void free_Cache()
{
int S = cache->S;
for (int i = 0; i < S; i++)
{
free(cache->line[i]);
}
free(cache->line);
free(cache);
}
int get_index(int op_s, int op_tag)
{
for (int i = 0; i < cache->E; i++)
{
if (cache->line[op_s][i].valid && cache->line[op_s][i].tag == op_tag)
return i;
}
return -1;
}
int find_LRU(int op_s)
{
int max_index = 0;
int max_stamp = 0;
for(int i = 0; i < cache->E; i++){
if(cache->line[op_s][i].time_tamp > max_stamp){
max_stamp = cache->line[op_s][i].time_tamp;
max_index = i;
}
}
return max_index;
}
int is_full(int op_s)
{
for (int i = 0; i < cache->E; i++)
{
if (cache->line[op_s][i].valid == 0)
return i;
}
return -1;
}
void update(int i, int op_s, int op_tag){
cache->line[op_s][i].valid=1;
cache->line[op_s][i].tag = op_tag;
for(int k = 0; k < cache->E; k++)
if(cache->line[op_s][k].valid==1)
cache->line[op_s][k].time_tamp++;
cache->line[op_s][i].time_tamp = 0;
}
void update_info(int op_tag, int op_s)
{
int index = get_index(op_s, op_tag);
if (index == -1)
{
miss_count++;
if (verbose)
printf("miss ");
int i = is_full(op_s);
if(i==-1){
eviction_count++;
if(verbose) printf("eviction");
i = find_LRU(op_s);
}
update(i,op_s,op_tag);
}
else{
hit_count++;
if(verbose)
printf("hit");
update(index,op_s,op_tag);
}
}
void get_trace(int s, int E, int b)
{
FILE *pFile;
pFile = fopen(t, "r");
if (pFile == NULL)
{
exit(-1);
}
char identifier;
unsigned address;
int size;
// Reading lines like " M 20,1" or "L 19,3"
while (fscanf(pFile, " %c %x,%d", &identifier, &address, &size) > 0) // I读不进来,忽略---size没啥用
{
//想办法先得到标记位和组序号
int op_tag = address >> (s + b);
int op_s = (address >> b) & ((unsigned)(-1) >> (8 * sizeof(unsigned) - s));
switch (identifier)
{
case 'M': //一次存储一次加载
update_info(op_tag, op_s);
update_info(op_tag, op_s);
break;
case 'L':
update_info(op_tag, op_s);
break;
case 'S':
update_info(op_tag, op_s);
break;
}
}
fclose(pFile);
}
void print_help()
{
printf("** A Cache Simulator by Deconx\n");
printf("Usage: ./csim-ref [-hv] -s <num> -E <num> -b <num> -t <file>\n");
printf("Options:\n");
printf("-h Print this help message.\n");
printf("-v Optional verbose flag.\n");
printf("-s <num> Number of set index bits.\n");
printf("-E <num> Number of lines per set.\n");
printf("-b <num> Number of block offset bits.\n");
printf("-t <file> Trace file.\n\n\n");
printf("Examples:\n");
printf("linux> ./csim -s 4 -E 1 -b 4 -t traces/yi.trace\n");
printf("linux> ./csim -v -s 8 -E 2 -b 4 -t traces/yi.trace\n");
}
int main(int argc, char *argv[])
{
char opt;
int s, E, b;
/*
* s:S=2^s是组的个数
* E:每组中有多少行
* b:B=2^b每个缓冲块的字节数
*/
while (-1 != (opt = getopt(argc, argv, "hvs:E:b:t:")))
{
switch (opt)
{
case 'h':
print_help();
exit(0);
case 'v':
verbose = 1;
break;
case 's':
s = atoi(optarg);
break;
case 'E':
E = atoi(optarg);
break;
case 'b':
b = atoi(optarg);
break;
case 't':
strcpy(t, optarg);
break;
default:
print_help();
exit(-1);
}
}
Init_Cache(s, E, b); //初始化一个cache
get_trace(s, E, b);
free_Cache();
// printSummary(hit_count, miss_count, eviction_count)
printSummary(hit_count, miss_count, eviction_count);
return 0;
}
在终端编译csim.c命令:
make
测试:
