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#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include "litmus.h"
#include "spinlocks.h"
#define NR_RESOURCES sizeof(resource_mask_t)*8
#define MEASURE TRUE
int events;
#if MEASURE==TRUE
static inline long diff_ns(const struct timespec *s, const struct timespec *e)
{
const int64_t ns_in_s = 1000000000LL;
struct timespec temp = *e;
temp.tv_sec -= s->tv_sec;
temp.tv_nsec -= s->tv_nsec;
if (temp.tv_nsec < 0) {
--temp.tv_sec;
temp.tv_nsec += ns_in_s;
}
return temp.tv_sec * ns_in_s + temp.tv_nsec;
}
#endif
void spin_init(spinlock_t *lock){
lock->serving = 0;
lock->next_ticket = 0;
}
void spin_lock(spinlock_t *lock){
int ticket = __sync_fetch_and_add(&(lock->next_ticket), 1);
// printf("%d:%d waiting for ticket %d serving %d\n",
// __sync_fetch_and_add(&events,1), gettid(), ticket, lock->serving);
while(lock->serving != ticket);
}
void spin_unlock(spinlock_t *lock){
lock->serving += 1;
}
void rwrnlp_init(rwrnlp *lock)
{
int i;
events = 0;
lock->wlocked = 0;
lock->wentitled = 0;
lock->unavailable = 0;
lock->enqueue = (spinlock_t*)(malloc(sizeof(spinlock_t)));
lock->state = (spinlock_t*)(malloc(sizeof(spinlock_t)));
for(i = 0; i < NR_RESOURCES; i++){
lock->whead[i] = 0;
lock->wtail[i] = 0;
}
for(i = 0; i < NR_CPUS; i++){
lock->enter[i] = 0;
lock->leave[i] = 0;
lock->curr[i] = 0;
}
spin_init(lock->enqueue);
spin_init(lock->state);
}
long rwrnlp_read_lock(rwrnlp *lock, resource_mask_t resources, int processor)
{
request *req;
#if MEASURE==TRUE
long overhead = 0;
struct timespec now, last;
clock_gettime(CLOCK_MONOTONIC, &last);
#endif
enter_np();
req = &lock->requests[processor][lock->curr[processor]];
req->resources = resources;
req->type = read_req;
req->status = waiting;
lock->enter[processor]+=1;
// printf("%d:%d rwrnlp_read_lock %lu\n",__sync_fetch_and_add(&events,1), gettid(), req->resources);
spin_lock(lock->state);
if((req->resources & lock->unavailable) == 0){
req->status = acquired;
}
spin_unlock(lock->state);
if(req->status != acquired){
// printf("%d:%d waiting to become entitled\n",__sync_fetch_and_add(&events,1), gettid());
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &now);
overhead += diff_ns(&last,&now);
#endif
while((req->resources & lock->wentitled) != 0);
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &last);
#endif
req->status = entitled;
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &now);
overhead += diff_ns(&last, &now);
#endif
// printf("%d:%d waiting to acquire\n", __sync_fetch_and_add(&events,1), gettid());
while((req->resources & lock->wlocked) != 0);
}
#if MEASURE==TRUE
else{
//acquire, but measure overheads
clock_gettime(CLOCK_MONOTONIC, &now);
overhead += diff_ns(&last, &now);
}
return overhead;
#else
return 0;
#endif
// printf("%d:%d reader satisfied\n", __sync_fetch_and_add(&events,1), gettid());
}
long rwrnlp_write_lock(rwrnlp *lock, resource_mask_t resources, int processor)
{
int r,i,start,end;
request *req, *contender;
resource_mask_t tmp = resources;
#if MEASURE==TRUE
struct timespec now, last;
long overhead = 0;
clock_gettime(CLOCK_MONOTONIC, &last);
#endif
enter_np();
// printf("%d:%d rwrnlp_write_lock\n", __sync_fetch_and_add(&events,1), gettid());
req = &lock->requests[processor][lock->curr[processor]];
req->resources = resources;
req->type = write_req;
req->status = waiting;
lock->enter[processor]+=1;
spin_lock(lock->enqueue);
r = ffsl(tmp);
while(r != 0){
r = r-1; // ffsl gives 1-indexed, since 0 is the return value for 0.
lock->wqueue[r][lock->wtail[r]] = req;
lock->wtail[r] = (lock->wtail[r] + 1) % NR_CPUS;
tmp &= ~(1<<r);
r = ffsl(tmp);
}
spin_unlock(lock->enqueue);
tmp = resources;
r = ffsl(tmp);
while(r != 0){
r = r-1;
// printf("%d:%d write waiting to become head of %d\n", __sync_fetch_and_add(&events,1), gettid(), r);
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &now);
overhead += diff_ns(&last, &now);
#endif
while(lock->wqueue[r][lock->whead[r]] != req);
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &last);
#endif
tmp &= ~(1<<r);
r = ffsl(tmp);
}
spin_lock(lock->state);
lock->unavailable |= req->resources;
req->status = entitled;
spin_unlock(lock->state);
for(i = 0; i < NR_CPUS; i++){
if(i != processor){
end = lock->leave[i];
contender = &lock->requests[i][lock->curr[processor]];
start = lock->enter[i];
if(start <= end ||
contender->type == write_req ||
contender->status == waiting ||
(contender->resources & req->resources) == 0)
continue;
// printf("%d:%d waiting for reader on processor %d\n", __sync_fetch_and_add(&events,1), gettid(), i);
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &now);
overhead += diff_ns(&last, &now);
#endif
while(lock->leave[i] < start);
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &last);
#endif
}
}
spin_lock(lock->state);
lock->wentitled &= ~(req->resources);
lock->wlocked |= req->resources;
spin_unlock(lock->state);
// printf("%d:%d writer satisfied\n", __sync_fetch_and_add(&events,1), gettid());
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &now);
overhead += diff_ns(&last, &now);
return overhead;
#else
return 0;
#endif
}
long rwrnlp_read_unlock(rwrnlp *lock, int processor)
{
#if MEASURE==TRUE
struct timespec now, last;
clock_gettime(CLOCK_MONOTONIC, &last);
#endif
lock->leave[processor] += 1;
lock->curr[processor] = (lock->curr[processor] + 1) % 2;
// printf("%d:%d rwrnlp_read_unlock\n", __sync_fetch_and_add(&events,1), gettid());
exit_np();
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &now);
return diff_ns(&last, &now);
#else
return 0;
#endif
}
long rwrnlp_write_unlock(rwrnlp *lock, int processor)
{
int r;
request *req;
resource_mask_t tmp;
#if MEASURE==TRUE
struct timespec now, last;
clock_gettime(CLOCK_MONOTONIC, &last);
#endif
req= &lock->requests[processor][lock->curr[processor]];
tmp = req->resources;
// printf("%d:%d rwrnlp_write_unlock\n", __sync_fetch_and_add(&events,1), gettid());
spin_lock(lock->state);
r = ffsl(tmp);
while(r != 0){
r = r-1; // ffsl gives 1-indexed, since 0 is the return value for 0.
lock->whead[r] = (lock->whead[r] + 1) % NR_CPUS;
tmp &= ~(1<<r);
r = ffsl(tmp);
}
lock->wlocked &= ~(req->resources);
lock->unavailable &= ~(req->resources);
spin_unlock(lock->state);
lock->leave[processor] += 1;
lock->curr[processor] = (lock->curr[processor] + 1) % 2;
// printf("%d:%d write unlocked %lu\n", __sync_fetch_and_add(&events,1), gettid(), req->resources);
// printf("unavailable %lu\nwentitled %lu\nwlocked %lu\n", lock->unavailable, lock->wentitled, lock->wlocked);
exit_np();
#if MEASURE==TRUE
clock_gettime(CLOCK_MONOTONIC, &now);
return diff_ns(&last, &now);
#else
return 0;
#endif
}
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