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提交 28e654af 创建 作者: Nickolai Zeldovich's avatar Nickolai Zeldovich
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combine epoch and epoch_depth.

get rid of gc_epoch_lock.
上级 eddb2693
隐藏空白字符变更
内嵌 并排
正在显示 包含 23 行增加 和 31 行删除
include/proc.hh
浏览文件 @ 28e654af
......@@ -57,9 +57,7 @@ struct proc : public rcu_freed {
SLIST_HEAD(childlist, proc) childq;
SLIST_ENTRY(proc) child_next;
struct condvar cv;
std::atomic<u64> epoch;
struct spinlock gc_epoch_lock;
std::atomic<u64> epoch_depth;
std::atomic<u64> epoch; // low 8 bits are depth count
char lockname[16];
int on_runq;
int cpu_pin;
......@@ -77,12 +75,11 @@ struct proc : public rcu_freed {
proc(int npid) : rcu_freed("proc"), vmap(0), brk(0), kstack(0),
state(EMBRYO), pid(npid), parent(0), tf(0), context(0), killed(0),
cwd(0), tsc(0), curcycles(0), cpuid(0), epoch(0), epoch_depth(0),
cwd(0), tsc(0), curcycles(0), cpuid(0), epoch(0),
on_runq(-1), cpu_pin(0), runq(0), oncv(0), cv_wakeup(0)
{
snprintf(lockname, sizeof(lockname), "cv:proc:%d", pid);
initlock(&lock, lockname+3, LOCKSTAT_PROC);
initlock(&gc_epoch_lock, lockname+3, LOCKSTAT_PROC);
initcondvar(&cv, lockname);
memset(&childq, 0, sizeof(childq));
......@@ -95,7 +92,6 @@ struct proc : public rcu_freed {
~proc() {
destroylock(&lock);
destroylock(&gc_epoch_lock);
destroycondvar(&cv);
}
......
kernel/gc.cc
浏览文件 @ 28e654af
......@@ -132,20 +132,22 @@ gc_delayfreelist(void)
if (gc_debug) {
cprintf("(%d,%d) (%s): min %lu global %lu\n", myproc()->cpuid, myproc()->pid, myproc()->name, min, global);
}
myproc()->epoch_depth++; // ensure enumerate's call to gc_begin_epoch doesn't have sideeffects
myproc()->epoch++; // ensure enumerate's call to gc_begin_epoch doesn't have sideeffects
xnspid->enumerate([&min](u32, proc *p)->bool{
// Some threads may never call begin/end_epoch(), and never update
// p->epoch, so gc_thread does it for them. XXX get rid off lock?
acquire(&p->gc_epoch_lock);
if (p->epoch_depth == 0)
p->epoch = global_epoch.load();
release(&p->gc_epoch_lock);
// p->epoch, so gc_thread does it for them.
u64 x = p->epoch.load();
if (!(x & 0xff)) {
cmpxch(&p->epoch, x, global_epoch.load() << 8);
x = p->epoch.load();
}
// cprintf("gc_min %d(%s): %lu %ld\n", p->pid, p->name, p->epoch, p->epoch_depth);
if (min > p->epoch)
min = p->epoch;
if (min > (x>>8))
min = (x>>8);
return false;
});
myproc()->epoch_depth--;
myproc()->epoch--;
if (min >= global) {
gc_move_to_tofree(min);
}
......@@ -158,7 +160,7 @@ gc_delayed(rcu_freed *e)
int c = mycpu()->id;
gc_state[c].ndelayed++;
u64 myepoch = myproc()->epoch;
u64 myepoch = (myproc()->epoch >> 8);
u64 minepoch = gc_state[c].delayed[myepoch % NEPOCH].epoch;
if (gc_debug)
cprintf("(%d, %d): gc_delayed: %lu ndelayed %d\n", c, myproc()->pid,
......@@ -176,24 +178,20 @@ void
gc_begin_epoch(void)
{
if (myproc() == NULL) return;
acquire(&myproc()->gc_epoch_lock);
if (myproc()->epoch_depth++ > 0)
goto done;
myproc()->epoch = global_epoch.load(); // not atomic, but it never goes backwards
u64 v = myproc()->epoch++;
if (v & 0xff)
return;
cmpxch(&myproc()->epoch, v+1, (global_epoch.load()<<8)+1);
// __sync_synchronize();
done:
(void) 0;
release(&myproc()->gc_epoch_lock);
}
void
gc_end_epoch(void)
{
if (myproc() == NULL) return;
acquire(&myproc()->gc_epoch_lock);
--myproc()->epoch_depth;
release(&myproc()->gc_epoch_lock);
if (myproc()->epoch_depth == 0 && gc_state[mycpu()->id].ndelayed > NGC)
u64 e = --myproc()->epoch;
if ((e & 0xff) == 0 && gc_state[mycpu()->id].ndelayed > NGC)
cv_wakeup(&gc_state[mycpu()->id].cv);
}
......@@ -221,7 +219,7 @@ gc_worker(void *x)
release(&wl);
gc_state[mycpu()->id].nrun++;
u64 global = global_epoch;
myproc()->epoch = global_epoch.load(); // move the gc thread to next epoch
myproc()->epoch = global_epoch.load() << 8; // move the gc thread to next epoch
for (i = gc_state[mycpu()->id].min_epoch; i < global-2; i++) {
int nfree = gc_free_tofreelist(&gc_state[mycpu()->id].tofree[i%NEPOCH].head, i);
gc_state[mycpu()->id].tofree[i%NEPOCH].epoch += NEPOCH;
......@@ -239,9 +237,7 @@ gc_worker(void *x)
void
initprocgc(struct proc *p)
{
p->epoch = global_epoch.load();
p->epoch_depth = 0;
initlock(&p->gc_epoch_lock, "per process gc_lock", 0);
p->epoch = global_epoch.load() << 8;
}
void
......
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