Re: 2.4.6 and ext3-2.4-0.9.1-246

Andrew Morton
2001-07-12T11:33:59Z

Mike Black wrote:
>
> Nope -- still locked up on 8 threads....however...it's apparently not RAID1
> causing this.

Well, aside from the RAID problems which we're triggering, you're
seeing interactions between RAID, ext3 and the VM. There's
another raid1 patch here, please.

> I'm repeating this now on my SCSI 7x36G RAID5 set and seeing similar
> behavior. It's a little better though since its SCSI.

RAID5 had a bug which would cause long stalls - ext3 triggered
it. It's fixed in 2.4.7-pre. I include that diff here, although
it'd be surprising if you were hitting it with that workload.

> ...
> I've got a vmstat running in a window and it pauses a lot. When I was
> testing the IDE RAID1 it paused (locked?) for a LONG time.

That's typical behaviour for an out-of-memory condition.

--- linux-2.4.6/drivers/md/raid1.c Wed Jul 4 18:21:26 2001
+++ lk-ext3/drivers/md/raid1.c Thu Jul 12 15:27:09 2001
@@ -46,6 +46,30 @@
#define PRINTK(x...) do { } while (0)
#endif

+#define __raid1_wait_event(wq, condition) \
+do { \
+ wait_queue_t __wait; \
+ init_waitqueue_entry(&__wait, current); \
+ \
+ add_wait_queue(&wq, &__wait); \
+ for (;;) { \
+ set_current_state(TASK_UNINTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ run_task_queue(&tq_disk); \
+ schedule(); \
+ } \
+ current->state = TASK_RUNNING; \
+ remove_wait_queue(&wq, &__wait); \
+} while (0)
+
+#define raid1_wait_event(wq, condition) \
+do { \
+ if (condition) \
+ break; \
+ __raid1_wait_event(wq, condition); \
+} while (0)
+

static mdk_personality_t raid1_personality;
static md_spinlock_t retry_list_lock = MD_SPIN_LOCK_UNLOCKED;
@@ -83,7 +107,7 @@ static struct buffer_head *raid1_alloc_b
cnt--;
} else {
PRINTK("raid1: waiting for %d bh\n", cnt);
- wait_event(conf->wait_buffer, conf->freebh_cnt >= cnt);
+ raid1_wait_event(conf->wait_buffer, conf->freebh_cnt >= cnt);
}
}
return bh;
@@ -170,7 +194,7 @@ static struct raid1_bh *raid1_alloc_r1bh
memset(r1_bh, 0, sizeof(*r1_bh));
return r1_bh;
}
- wait_event(conf->wait_buffer, conf->freer1);
+ raid1_wait_event(conf->wait_buffer, conf->freer1);
} while (1);
}

--- linux-2.4.6/drivers/md/raid5.c Wed Jul 4 18:21:26 2001
+++ lk-ext3/drivers/md/raid5.c Thu Jul 12 21:31:55 2001
@@ -66,10 +66,11 @@ static inline void __release_stripe(raid
BUG();
if (atomic_read(&conf->active_stripes)==0)
BUG();
- if (test_bit(STRIPE_DELAYED, &sh->state))
- list_add_tail(&sh->lru, &conf->delayed_list);
- else if (test_bit(STRIPE_HANDLE, &sh->state)) {
- list_add_tail(&sh->lru, &conf->handle_list);
+ if (test_bit(STRIPE_HANDLE, &sh->state)) {
+ if (test_bit(STRIPE_DELAYED, &sh->state))
+ list_add_tail(&sh->lru, &conf->delayed_list);
+ else
+ list_add_tail(&sh->lru, &conf->handle_list);
md_wakeup_thread(conf->thread);
} else {
if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
@@ -1167,10 +1168,9 @@ static void raid5_unplug_device(void *da

raid5_activate_delayed(conf);

- if (conf->plugged) {
- conf->plugged = 0;
- md_wakeup_thread(conf->thread);
- }
+ conf->plugged = 0;
+ md_wakeup_thread(conf->thread);
+
spin_unlock_irqrestore(&conf->device_lock, flags);
}