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提交 dbc11d57 创建 作者: Frans Kaashoek's avatar Frans Kaashoek
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Copy user-level changes back into kernel

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gc.c
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...@@ -13,7 +13,7 @@ ...@@ -13,7 +13,7 @@
// a process maintain an epoch (>= global_epoch) // a process maintain an epoch (>= global_epoch)
// one gc thread and state (e.g., NEPOCH delaylists and one tofreelists) per core // one gc thread and state (e.g., NEPOCH delaylists and one tofreelists) per core
// a process add to its core epoch's delayed freelist on delayed_free // a process add to its core epoch's delayed freelist on delayed_free
// a gcc performs two jobs: // a gcc thread performs two jobs:
// 1. one gcc thread perform step 1: // 1. one gcc thread perform step 1:
// updates a thread's epoch, when not in an epoch // updates a thread's epoch, when not in an epoch
// compute min over all process's epochs, and sets global_epoch to min // compute min over all process's epochs, and sets global_epoch to min
...@@ -24,6 +24,8 @@ ...@@ -24,6 +24,8 @@
enum { gc_debug = 0 }; enum { gc_debug = 0 };
#define NGC 10000
struct gc { struct gc {
u64 epoch; u64 epoch;
struct gc *next; struct gc *next;
...@@ -48,6 +50,9 @@ static struct gc_state { ...@@ -48,6 +50,9 @@ static struct gc_state {
struct gc tofree[NEPOCH]; struct gc tofree[NEPOCH];
int ndelayed; int ndelayed;
int min_epoch; int min_epoch;
int nrun;
int nfree;
int cnt;
} __mpalign__ gc_state[NCPU] __mpalign__; } __mpalign__ gc_state[NCPU] __mpalign__;
static struct { struct spinlock l __mpalign__; } gc_lock; static struct { struct spinlock l __mpalign__; } gc_lock;
...@@ -58,7 +63,7 @@ gc_alloc() ...@@ -58,7 +63,7 @@ gc_alloc()
{ {
struct gc *r = kmalloc(sizeof(struct gc)); struct gc *r = kmalloc(sizeof(struct gc));
assert(r); assert(r);
gc_state[mycpu()->id].ndelayed++; __sync_fetch_and_add(&gc_state[mycpu()->id].ndelayed, 1);
return r; return r;
} }
...@@ -66,11 +71,14 @@ static void * ...@@ -66,11 +71,14 @@ static void *
gc_min(void *vkey, void *v, void *arg){ gc_min(void *vkey, void *v, void *arg){
u64 *min_epoch_p = arg; u64 *min_epoch_p = arg;
struct proc *p = (struct proc *) v; struct proc *p = (struct proc *) v;
// 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); acquire(&p->gc_epoch_lock);
if (p->epoch_depth == 0) { if (p->epoch_depth == 0) {
p->epoch = global_epoch; p->epoch = global_epoch;
} }
release(&p->gc_epoch_lock); release(&p->gc_epoch_lock);
// cprintf("gc_min %d(%s): %lu %ld\n", p->pid, p->name, p->epoch, p->epoch_depth);
if (*min_epoch_p > p->epoch) { if (*min_epoch_p > p->epoch) {
*min_epoch_p = p->epoch; *min_epoch_p = p->epoch;
} }
...@@ -147,8 +155,8 @@ static void ...@@ -147,8 +155,8 @@ static void
gc_move_to_tofree(u64 epoch) gc_move_to_tofree(u64 epoch)
{ {
if (gc_debug) if (gc_debug)
cprintf("%d: free epoch %ld\n", mycpu()->id, epoch); cprintf("%d: move epoch %ld to tofreelist\n", mycpu()->id, epoch);
for (int c = 0; c < NCPU; c++) { for (int c = 0; c < ncpu; c++) {
gc_move_to_tofree_cpu(c, epoch); gc_move_to_tofree_cpu(c, epoch);
} }
int ok = __sync_bool_compare_and_swap(&global_epoch, epoch, epoch+1); int ok = __sync_bool_compare_and_swap(&global_epoch, epoch, epoch+1);
...@@ -166,12 +174,15 @@ gc_delayfreelist(void) ...@@ -166,12 +174,15 @@ gc_delayfreelist(void)
u64 global = global_epoch; u64 global = global_epoch;
u64 min = global; u64 min = global;
// make that global_epoch doesn't run into a core's min_epoch // make that global_epoch doesn't run into a core's min_epoch
for (int c = 0; c < NCPU; c++) { for (int c = 0; c < ncpu; c++) {
int w = gc_state[c].min_epoch + NEPOCH-1; int w = gc_state[c].min_epoch + NEPOCH-1;
if (w < min) { if (w < min) {
min = w; min = w;
} }
} }
if (gc_debug) {
cprintf("(%d,%d) (%s): min %lu global %lu\n", myproc()->cpuid, myproc()->pid, myproc()->name, min, global);
}
myproc()->epoch_depth++;// ensure ns_enumate's call to gc_begin_epoch doesn't have sideeffects myproc()->epoch_depth++;// ensure ns_enumate's call to gc_begin_epoch doesn't have sideeffects
ns_enumerate(nspid, gc_min, &min); ns_enumerate(nspid, gc_min, &min);
myproc()->epoch_depth--; myproc()->epoch_depth--;
...@@ -229,7 +240,9 @@ gc_delayed2(int a1, u64 a2, void (*dofree)(int,u64)) ...@@ -229,7 +240,9 @@ gc_delayed2(int a1, u64 a2, void (*dofree)(int,u64))
void void
gc_start(void) gc_start(void)
{ {
cv_wakeup(&gc_state[mycpu()->id].cv); // XXX hack?
if (gc_state[mycpu()->id].cnt++ % 10000 == 0)
cv_wakeup(&gc_state[mycpu()->id].cv);
} }
void void
...@@ -252,8 +265,19 @@ gc_end_epoch(void) ...@@ -252,8 +265,19 @@ gc_end_epoch(void)
acquire(&myproc()->gc_epoch_lock); acquire(&myproc()->gc_epoch_lock);
--myproc()->epoch_depth; --myproc()->epoch_depth;
release(&myproc()->gc_epoch_lock); release(&myproc()->gc_epoch_lock);
if (myproc()->epoch_depth == 0 && gc_state[mycpu()->id].ndelayed > NGC)
gc_start();
}
void gc_dumpstat(void)
{
for (int i = 0; i < ncpu; i++) {
cprintf("worker %d: %d %d\n", i, gc_state[i].nrun, gc_state[i].nfree);
}
} }
static void static void
gc_worker(void *x) gc_worker(void *x)
{ {
...@@ -268,14 +292,17 @@ gc_worker(void *x) ...@@ -268,14 +292,17 @@ gc_worker(void *x)
acquire(&wl); acquire(&wl);
cv_sleep(&gc_state[mycpu()->id].cv, &wl); cv_sleep(&gc_state[mycpu()->id].cv, &wl);
release(&wl); release(&wl);
gc_state[mycpu()->id].nrun++;
u64 global = global_epoch; u64 global = global_epoch;
myproc()->epoch = global_epoch; // move the gc thread to next epoch
for (i = gc_state[mycpu()->id].min_epoch; i < global-2; i++) { for (i = gc_state[mycpu()->id].min_epoch; i < global-2; i++) {
int nfree = gc_free_tofreelist(&(gc_state[mycpu()->id].tofree[i%NEPOCH].next), i); int nfree = gc_free_tofreelist(&(gc_state[mycpu()->id].tofree[i%NEPOCH].next), i);
gc_state[mycpu()->id].tofree[i%NEPOCH].epoch += NEPOCH; gc_state[mycpu()->id].tofree[i%NEPOCH].epoch += NEPOCH;
if (gc_debug && nfree > 0) { __sync_fetch_and_sub(&gc_state[mycpu()->id].ndelayed, nfree);
if (0 && nfree > 0) {
cprintf("%d: epoch %lu freed %d\n", mycpu()->id, i, nfree); cprintf("%d: epoch %lu freed %d\n", mycpu()->id, i, nfree);
} }
gc_state[mycpu()->id].nfree += nfree;
} }
gc_state[mycpu()->id].min_epoch = i; gc_state[mycpu()->id].min_epoch = i;
gc_delayfreelist(); gc_delayfreelist();
...@@ -286,17 +313,17 @@ void ...@@ -286,17 +313,17 @@ void
initprocgc(struct proc *p) initprocgc(struct proc *p)
{ {
p->epoch = global_epoch; p->epoch = global_epoch;
p->epoch_depth = 0;
initlock(&p->gc_epoch_lock, "per process gc_lock"); initlock(&p->gc_epoch_lock, "per process gc_lock");
} }
void void
initgc(void) initgc(void)
{ {
initlock(&gc_lock.l, "gc"); initlock(&gc_lock.l, "gc");
global_epoch = NEPOCH-2; global_epoch = NEPOCH-2;
for (int i = 0; i < NCPU; i++) { for (int i = 0; i < ncpu; i++) {
for (int j = 0; j < NEPOCH; j++) { for (int j = 0; j < NEPOCH; j++) {
gc_state[i].delayed[j].epoch = j; gc_state[i].delayed[j].epoch = j;
gc_state[i].tofree[j].epoch = j; gc_state[i].tofree[j].epoch = j;
...@@ -304,7 +331,7 @@ initgc(void) ...@@ -304,7 +331,7 @@ initgc(void)
initcondvar(&gc_state[i].cv, "gc_cv"); initcondvar(&gc_state[i].cv, "gc_cv");
} }
for (u32 c = 0; c < NCPU; c++) { for (u32 c = 0; c < ncpu; c++) {
struct proc *gcp; struct proc *gcp;
gcp = threadalloc(gc_worker, NULL); gcp = threadalloc(gc_worker, NULL);
...@@ -315,6 +342,7 @@ initgc(void) ...@@ -315,6 +342,7 @@ initgc(void)
gcp->cpuid = c; gcp->cpuid = c;
gcp->cpu_pin = 1; gcp->cpu_pin = 1;
acquire(&gcp->lock); acquire(&gcp->lock);
gcp->state = RUNNABLE;
addrun(gcp); addrun(gcp);
release(&gcp->lock); release(&gcp->lock);
} }
......
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