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SubjectRe: 2x Oracle slowdown from 2.2.16 to 2.4.4
Andrew Morton wrote:
>
> Lance Larsh wrote:
> >
> > And while we're talking about comparing configurations, I'll mention that
> > I'm currently trying to compare raw and ext2 (no lvm in either case).
>
> It would be interesting to see some numbers for ext3 with full
> data journalling.
>
> Some preliminary testing by Neil Brown shows that ext3 is 1.5x faster
> than ext2 when used with knfsd, mounted synchronously. (This uses
> O_SYNC internally).

I just did some testing with local filesystems - running `dbench 4'
on ext2-on-iDE and ext3-on-IDE, where dbench was altered to open
files O_SYNC. Journal size was 400 megs, mount options `data=journal'

ext2: Throughput 2.71849 MB/sec (NB=3.39812 MB/sec 27.1849 MBit/sec)
ext3: Throughput 12.3623 MB/sec (NB=15.4529 MB/sec 123.623 MBit/sec)

ext3 patches are at http://www.uow.edu.au/~andrewm/linux/ext3/

The difference will be less dramatic with large, individual writes.

Be aware though that ext3 breaks both RAID1 and RAID5. This
RAID patch should help:


--- 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);
}
-
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