DragonFly kernel List (threaded) for 2003-07
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Re: MESI Caching work start (was Re: caching and userapi)
On Sat, Jul 19, 2003 at 01:20:18PM -0700, Matthew Dillon wrote:
>
> :Matt, looking by my books, I've found out references to MESI protocol
> :on the PowerPC 604 manual (page 3-11), which it uses for it's caches.
[ snip ]
I've been coding a bit of this MESI protocol. Unfinished test code attached.
Greets, Antonio.
--
1. Dado un programa, siempre tiene al menos un fallo.
2. Dadas varias lineas de codigo, siempre se pueden acortar a menos lineas.
3. Por induccion, todos los programas se pueden
reducir a una linea que no funciona.
#include <stdio.h>
#define NCPU 8
#define NMEM 10
#define NBUS 50
#define STATE_MODIFIED 0
#define STATE_EXCLUSIVE 1
#define STATE_SHARED 2
#define STATE_INVALID 3
#define BUS_READ 0
#define BUS_READW 1
#define BUS_INVALIDATE 2
#define BUS_PUSH 3
#define PROC_READ 0
#define PROC_READW 1
#define PROC_WRITE 2
#define PROC_INVALIDATE 3
#define PROC_COUNT 4
struct busentry{
int addr;
int data;
int status;
};
struct busentry bus[NBUS];
struct busentry cache[NCPU][NMEM];
int readp[NCPU];
int writep;
int rnddata[3];
int rnd(void)
{
int a,b,c;
a = rnddata[0];
rnddata[0] = b = rnddata[1];
rnddata[1] = c = rnddata[2];
rnddata[2] = a + b;
return a * b + c;
}
void init(void)
{
struct busentry *b;
int i,j;
for(i = 0 ; i < NCPU ; i++){
readp[i] = -1;
for(j = 0 ; j < NMEM ; j++){
b = &cache[i][j];
b->addr = j;
b->data = i ? 999 : j;
b->status = i ? STATE_INVALID : STATE_EXCLUSIVE;
}
}
writep = 0;
rnddata[0] = 2;
rnddata[1] = 5;
rnddata[2] = 9;
}
void dump(void)
{
char a;
int i,j;
char s1[3 * NCPU + 1];
char s2[3 * NCPU + 1];
struct busentry *b;
for(j = 0 ; j < NMEM ; j++){
for(i = 0 ; i < NCPU ; i++){
b = &cache[i][j];
switch(b->status){
case STATE_MODIFIED: a = 'm'; break;
case STATE_EXCLUSIVE: a = 'e'; break;
case STATE_SHARED: a = 's'; break;
case STATE_INVALID: a = 'i'; break;
}
sprintf(&s1[i], "%c", a);
sprintf(&s2[i*3], " %02d", b->data);
}
s1[i] = 0;
s2[i*3 - 2] = 0;
printf("dump: %s %s %02d\n", s1, s2);
}
}
void bus_process(int cpu)
{
struct busentry *b,*c;
int i,j;
if(cpu >= NCPU) return;
b = &bus[++readp[cpu]];
c = &cache[cpu][b->addr];
bus_process(cpu + 1);
}
void bus_send(int addr, int data, int status)
{
struct busentry *b = &bus[writep];
b->addr = addr;
b->data = data;
b->status = status;
++writep;
bus_process(0);
}
void bus_read_invalid(struct busentry *b, int addr){};
void bus_readw_shared(struct busentry *b, int addr){};
void bus_readw_invalid(struct busentry *b, int addr){};
void bus_write_shared(struct busentry *b, int addr, int data){};
void bus_write_invalid(struct busentry *b, int addr, int data){};
void bus_invalidate_modified(struct busentry *b, int addr){};
void bus_invalidate_exclusive(struct busentry *b, int addr){};
void bus_invalidate_shared(struct busentry *b, int addr){};
void proc(int cpu, struct busentry *b)
{
struct busentry *c = &cache[cpu][b->addr];
int cc = c->status;
int addr = b->addr;
int data = b->data;
switch(b->status){
case PROC_READ:
switch(cc){
case STATE_MODIFIED: break;
case STATE_EXCLUSIVE: break;
case STATE_SHARED: break;
case STATE_INVALID: bus_read_invalid(c, addr); break;
}
break;
case PROC_READW:
switch(cc){
case STATE_MODIFIED: break;
case STATE_EXCLUSIVE: break;
case STATE_SHARED: bus_readw_shared(c, addr); break;
case STATE_INVALID: bus_readw_invalid(c, addr); break;
}
break;
case PROC_WRITE:
switch(cc){
case STATE_MODIFIED: break;
case STATE_EXCLUSIVE: c->status = STATE_MODIFIED; break;
case STATE_SHARED: bus_write_shared(c, addr, data); break;
case STATE_INVALID: bus_write_invalid(c, addr, data); break;
}
break;
case PROC_INVALIDATE:
switch(cc){
case STATE_MODIFIED: bus_invalidate_modified(c, addr); break;
case STATE_EXCLUSIVE: bus_invalidate_exclusive(c, addr); break;
case STATE_SHARED: bus_invalidate_shared(c, addr); break;
case STATE_INVALID: break;
}
break;
}
}
int main(int argc, char **argv)
{
int cpu;
struct busentry b;
init();
dump();
cpu = rnd() % NCPU;
b.addr = rnd() % NMEM;
b.data = rnd() % (NCPU * NMEM % 99);
b.status = rnd() % PROC_COUNT;
proc(cpu, &b);
return 0;
}
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