From f665c0f852316ff99e9eb7f71f34d43003f8e139 Mon Sep 17 00:00:00 2001
From: Stefan Priebe <s.priebe@profihost.ag>
Date: Sat, 16 Nov 2013 21:26:52 +0100
Subject: bcache: kthread don't set writeback task to INTERUPTIBLE
at the beginning (schedule_timout_interuptible) and others
do his on their own
This prevents wrong load average calculation (load of 1 per thread)
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
---
drivers/md/bcache/writeback.c | 2 --
1 file changed, 2 deletions(-)
(limited to 'drivers/md/bcache/writeback.c')
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 99053b1251b..484e57d7012 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -500,8 +500,6 @@ int bch_cached_dev_writeback_init(struct cached_dev *dc)
if (IS_ERR(dc->writeback_thread))
return PTR_ERR(dc->writeback_thread);
- set_task_state(dc->writeback_thread, TASK_INTERRUPTIBLE);
-
INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
schedule_delayed_work(&dc->writeback_rate_update,
dc->writeback_rate_update_seconds * HZ);
--
cgit v1.2.3-70-g09d2
From ce2b3f595e1c56639085645e0130426e443008c0 Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kmo@daterainc.com>
Date: Thu, 28 Nov 2013 17:28:37 -0800
Subject: bcache: Use uninterruptible sleep in writeback
We're just waiting on kthread_should_stop(), nothing else, so
interruptible sleep was wrong here.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
---
drivers/md/bcache/writeback.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'drivers/md/bcache/writeback.c')
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 484e57d7012..3cd931d3f26 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -241,7 +241,7 @@ static void read_dirty(struct cached_dev *dc)
if (KEY_START(&w->key) != dc->last_read ||
jiffies_to_msecs(delay) > 50)
while (!kthread_should_stop() && delay)
- delay = schedule_timeout_interruptible(delay);
+ delay = schedule_timeout_uninterruptible(delay);
dc->last_read = KEY_OFFSET(&w->key);
@@ -438,7 +438,7 @@ static int bch_writeback_thread(void *arg)
while (delay &&
!kthread_should_stop() &&
!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
- delay = schedule_timeout_interruptible(delay);
+ delay = schedule_timeout_uninterruptible(delay);
}
}
--
cgit v1.2.3-70-g09d2
From 16749c23c00c686ed168471963e3ddb0f3fcd855 Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kmo@daterainc.com>
Date: Mon, 11 Nov 2013 13:58:34 -0800
Subject: bcache: New writeback PD controller
The old writeback PD controller could get into states where it had throttled all
the way down and take way too long to recover - it was too complicated to really
understand what it was doing.
This rewrites a good chunk of it to hopefully be simpler and make more sense,
and it also pays more attention to units which should make the behaviour a bit
easier to understand.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
---
drivers/md/bcache/bcache.h | 6 +++---
drivers/md/bcache/sysfs.c | 50 +++++++++++++++++++++++++------------------
drivers/md/bcache/util.c | 8 ++++++-
drivers/md/bcache/writeback.c | 47 ++++++++++++++++++++--------------------
4 files changed, 62 insertions(+), 49 deletions(-)
(limited to 'drivers/md/bcache/writeback.c')
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index a7b1a7631ed..754f4317748 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -373,14 +373,14 @@ struct cached_dev {
unsigned char writeback_percent;
unsigned writeback_delay;
- int writeback_rate_change;
- int64_t writeback_rate_derivative;
uint64_t writeback_rate_target;
+ int64_t writeback_rate_proportional;
+ int64_t writeback_rate_derivative;
+ int64_t writeback_rate_change;
unsigned writeback_rate_update_seconds;
unsigned writeback_rate_d_term;
unsigned writeback_rate_p_term_inverse;
- unsigned writeback_rate_d_smooth;
};
enum alloc_watermarks {
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 80d4c2bee18..a1f85612f0b 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -83,7 +83,6 @@ rw_attribute(writeback_rate);
rw_attribute(writeback_rate_update_seconds);
rw_attribute(writeback_rate_d_term);
rw_attribute(writeback_rate_p_term_inverse);
-rw_attribute(writeback_rate_d_smooth);
read_attribute(writeback_rate_debug);
read_attribute(stripe_size);
@@ -129,31 +128,41 @@ SHOW(__bch_cached_dev)
var_printf(writeback_running, "%i");
var_print(writeback_delay);
var_print(writeback_percent);
- sysfs_print(writeback_rate, dc->writeback_rate.rate);
+ sysfs_hprint(writeback_rate, dc->writeback_rate.rate << 9);
var_print(writeback_rate_update_seconds);
var_print(writeback_rate_d_term);
var_print(writeback_rate_p_term_inverse);
- var_print(writeback_rate_d_smooth);
if (attr == &sysfs_writeback_rate_debug) {
+ char rate[20];
char dirty[20];
- char derivative[20];
char target[20];
- bch_hprint(dirty,
- bcache_dev_sectors_dirty(&dc->disk) << 9);
- bch_hprint(derivative, dc->writeback_rate_derivative << 9);
+ char proportional[20];
+ char derivative[20];
+ char change[20];
+ s64 next_io;
+
+ bch_hprint(rate, dc->writeback_rate.rate << 9);
+ bch_hprint(dirty, bcache_dev_sectors_dirty(&dc->disk) << 9);
bch_hprint(target, dc->writeback_rate_target << 9);
+ bch_hprint(proportional,dc->writeback_rate_proportional << 9);
+ bch_hprint(derivative, dc->writeback_rate_derivative << 9);
+ bch_hprint(change, dc->writeback_rate_change << 9);
+
+ next_io = div64_s64(dc->writeback_rate.next - local_clock(),
+ NSEC_PER_MSEC);
return sprintf(buf,
- "rate:\t\t%u\n"
- "change:\t\t%i\n"
+ "rate:\t\t%s/sec\n"
"dirty:\t\t%s\n"
+ "target:\t\t%s\n"
+ "proportional:\t%s\n"
"derivative:\t%s\n"
- "target:\t\t%s\n",
- dc->writeback_rate.rate,
- dc->writeback_rate_change,
- dirty, derivative, target);
+ "change:\t\t%s/sec\n"
+ "next io:\t%llims\n",
+ rate, dirty, target, proportional,
+ derivative, change, next_io);
}
sysfs_hprint(dirty_data,
@@ -189,6 +198,7 @@ STORE(__cached_dev)
struct kobj_uevent_env *env;
#define d_strtoul(var) sysfs_strtoul(var, dc->var)
+#define d_strtoul_nonzero(var) sysfs_strtoul_clamp(var, dc->var, 1, INT_MAX)
#define d_strtoi_h(var) sysfs_hatoi(var, dc->var)
sysfs_strtoul(data_csum, dc->disk.data_csum);
@@ -197,16 +207,15 @@ STORE(__cached_dev)
d_strtoul(writeback_metadata);
d_strtoul(writeback_running);
d_strtoul(writeback_delay);
- sysfs_strtoul_clamp(writeback_rate,
- dc->writeback_rate.rate, 1, 1000000);
+
sysfs_strtoul_clamp(writeback_percent, dc->writeback_percent, 0, 40);
- d_strtoul(writeback_rate_update_seconds);
+ sysfs_strtoul_clamp(writeback_rate,
+ dc->writeback_rate.rate, 1, INT_MAX);
+
+ d_strtoul_nonzero(writeback_rate_update_seconds);
d_strtoul(writeback_rate_d_term);
- d_strtoul(writeback_rate_p_term_inverse);
- sysfs_strtoul_clamp(writeback_rate_p_term_inverse,
- dc->writeback_rate_p_term_inverse, 1, INT_MAX);
- d_strtoul(writeback_rate_d_smooth);
+ d_strtoul_nonzero(writeback_rate_p_term_inverse);
d_strtoi_h(sequential_cutoff);
d_strtoi_h(readahead);
@@ -313,7 +322,6 @@ static struct attribute *bch_cached_dev_files[] = {
&sysfs_writeback_rate_update_seconds,
&sysfs_writeback_rate_d_term,
&sysfs_writeback_rate_p_term_inverse,
- &sysfs_writeback_rate_d_smooth,
&sysfs_writeback_rate_debug,
&sysfs_dirty_data,
&sysfs_stripe_size,
diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
index 462214eeacb..bb37618e766 100644
--- a/drivers/md/bcache/util.c
+++ b/drivers/md/bcache/util.c
@@ -209,7 +209,13 @@ uint64_t bch_next_delay(struct bch_ratelimit *d, uint64_t done)
{
uint64_t now = local_clock();
- d->next += div_u64(done, d->rate);
+ d->next += div_u64(done * NSEC_PER_SEC, d->rate);
+
+ if (time_before64(now + NSEC_PER_SEC, d->next))
+ d->next = now + NSEC_PER_SEC;
+
+ if (time_after64(now - NSEC_PER_SEC * 2, d->next))
+ d->next = now - NSEC_PER_SEC * 2;
return time_after64(d->next, now)
? div_u64(d->next - now, NSEC_PER_SEC / HZ)
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 3cd931d3f26..6c44fe059c2 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -30,38 +30,40 @@ static void __update_writeback_rate(struct cached_dev *dc)
/* PD controller */
- int change = 0;
- int64_t error;
int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
int64_t derivative = dirty - dc->disk.sectors_dirty_last;
+ int64_t proportional = dirty - target;
+ int64_t change;
dc->disk.sectors_dirty_last = dirty;
- derivative *= dc->writeback_rate_d_term;
- derivative = clamp(derivative, -dirty, dirty);
+ /* Scale to sectors per second */
- derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
- dc->writeback_rate_d_smooth, 0);
+ proportional *= dc->writeback_rate_update_seconds;
+ proportional = div_s64(proportional, dc->writeback_rate_p_term_inverse);
- /* Avoid divide by zero */
- if (!target)
- goto out;
+ derivative = div_s64(derivative, dc->writeback_rate_update_seconds);
- error = div64_s64((dirty + derivative - target) << 8, target);
+ derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
+ (dc->writeback_rate_d_term /
+ dc->writeback_rate_update_seconds) ?: 1, 0);
+
+ derivative *= dc->writeback_rate_d_term;
+ derivative = div_s64(derivative, dc->writeback_rate_p_term_inverse);
- change = div_s64((dc->writeback_rate.rate * error) >> 8,
- dc->writeback_rate_p_term_inverse);
+ change = proportional + derivative;
/* Don't increase writeback rate if the device isn't keeping up */
if (change > 0 &&
time_after64(local_clock(),
- dc->writeback_rate.next + 10 * NSEC_PER_MSEC))
+ dc->writeback_rate.next + NSEC_PER_MSEC))
change = 0;
dc->writeback_rate.rate =
- clamp_t(int64_t, dc->writeback_rate.rate + change,
+ clamp_t(int64_t, (int64_t) dc->writeback_rate.rate + change,
1, NSEC_PER_MSEC);
-out:
+
+ dc->writeback_rate_proportional = proportional;
dc->writeback_rate_derivative = derivative;
dc->writeback_rate_change = change;
dc->writeback_rate_target = target;
@@ -87,15 +89,11 @@ static void update_writeback_rate(struct work_struct *work)
static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
{
- uint64_t ret;
-
if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
!dc->writeback_percent)
return 0;
- ret = bch_next_delay(&dc->writeback_rate, sectors * 10000000ULL);
-
- return min_t(uint64_t, ret, HZ);
+ return bch_next_delay(&dc->writeback_rate, sectors);
}
struct dirty_io {
@@ -476,6 +474,8 @@ void bch_sectors_dirty_init(struct cached_dev *dc)
bch_btree_map_keys(&op.op, dc->disk.c, &KEY(op.inode, 0, 0),
sectors_dirty_init_fn, 0);
+
+ dc->disk.sectors_dirty_last = bcache_dev_sectors_dirty(&dc->disk);
}
int bch_cached_dev_writeback_init(struct cached_dev *dc)
@@ -490,10 +490,9 @@ int bch_cached_dev_writeback_init(struct cached_dev *dc)
dc->writeback_delay = 30;
dc->writeback_rate.rate = 1024;
- dc->writeback_rate_update_seconds = 30;
- dc->writeback_rate_d_term = 16;
- dc->writeback_rate_p_term_inverse = 64;
- dc->writeback_rate_d_smooth = 8;
+ dc->writeback_rate_update_seconds = 5;
+ dc->writeback_rate_d_term = 30;
+ dc->writeback_rate_p_term_inverse = 6000;
dc->writeback_thread = kthread_create(bch_writeback_thread, dc,
"bcache_writeback");
--
cgit v1.2.3-70-g09d2