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authorMikulas Patocka <mpatocka@redhat.com>2021-06-28 15:59:37 +0200
committerMike Snitzer <snitzer@redhat.com>2021-06-28 22:30:13 +0200
commit5c0de3d72f8c05678ed769bea24e98128f7ab570 (patch)
tree9d41547dfdf367e5969af1244180d48564a1cc5b /drivers
parentdm writecache: pause writeback if cache full and origin being written directly (diff)
downloadlinux-5c0de3d72f8c05678ed769bea24e98128f7ab570.tar.xz
linux-5c0de3d72f8c05678ed769bea24e98128f7ab570.zip
dm writecache: make writeback pause configurable
Commit 95b88f4d71cb953e02206be3c757083601391a0f ("dm writecache: pause writeback if cache full and origin being written directly") introduced a code that pauses cache flushing if we are issuing writes directly to the origin. Improve that initial commit by making the timeout code configurable (via the option "pause_writeback"). Also change the default from 1s to 3s because it performed better. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/dm-io-tracker.h12
-rw-r--r--drivers/md/dm-writecache.c48
2 files changed, 52 insertions, 8 deletions
diff --git a/drivers/md/dm-io-tracker.h b/drivers/md/dm-io-tracker.h
index 1dcf01f9f066..bdcc6273ebf0 100644
--- a/drivers/md/dm-io-tracker.h
+++ b/drivers/md/dm-io-tracker.h
@@ -45,6 +45,18 @@ static inline bool dm_iot_idle_for(struct dm_io_tracker *iot, unsigned long j)
return r;
}
+static inline unsigned long dm_iot_idle_time(struct dm_io_tracker *iot)
+{
+ unsigned long r = 0;
+
+ spin_lock_irq(&iot->lock);
+ if (!iot->in_flight)
+ r = jiffies - iot->idle_time;
+ spin_unlock_irq(&iot->lock);
+
+ return r;
+}
+
static inline void dm_iot_io_begin(struct dm_io_tracker *iot, sector_t len)
{
spin_lock_irq(&iot->lock);
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index d70342c9003a..e21e29e81bbf 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -30,6 +30,7 @@
#define AUTOCOMMIT_MSEC 1000
#define MAX_AGE_DIV 16
#define MAX_AGE_UNSPECIFIED -1UL
+#define PAUSE_WRITEBACK (HZ * 3)
#define BITMAP_GRANULARITY 65536
#if BITMAP_GRANULARITY < PAGE_SIZE
@@ -125,6 +126,7 @@ struct dm_writecache {
size_t freelist_high_watermark;
size_t freelist_low_watermark;
unsigned long max_age;
+ unsigned long pause;
unsigned uncommitted_blocks;
unsigned autocommit_blocks;
@@ -174,11 +176,13 @@ struct dm_writecache {
bool cleaner:1;
bool cleaner_set:1;
bool metadata_only:1;
+ bool pause_set:1;
unsigned high_wm_percent_value;
unsigned low_wm_percent_value;
unsigned autocommit_time_value;
unsigned max_age_value;
+ unsigned pause_value;
unsigned writeback_all;
struct workqueue_struct *writeback_wq;
@@ -1470,9 +1474,11 @@ bio_copy:
}
unlock_remap_origin:
- if (bio_data_dir(bio) != READ) {
- dm_iot_io_begin(&wc->iot, 1);
- bio->bi_private = (void *)2;
+ if (likely(wc->pause != 0)) {
+ if (bio_op(bio) == REQ_OP_WRITE) {
+ dm_iot_io_begin(&wc->iot, 1);
+ bio->bi_private = (void *)2;
+ }
}
bio_set_dev(bio, wc->dev->bdev);
wc_unlock(wc);
@@ -1837,10 +1843,19 @@ static void writecache_writeback(struct work_struct *work)
dm_kcopyd_client_flush(wc->dm_kcopyd);
}
- if (!wc->writeback_all && !dm_suspended(wc->ti)) {
- while (!dm_iot_idle_for(&wc->iot, HZ)) {
- cond_resched();
- msleep(1000);
+ if (likely(wc->pause != 0)) {
+ while (1) {
+ unsigned long idle;
+ if (unlikely(wc->cleaner) || unlikely(wc->writeback_all) ||
+ unlikely(dm_suspended(wc->ti)))
+ break;
+ idle = dm_iot_idle_time(&wc->iot);
+ if (idle >= wc->pause)
+ break;
+ idle = wc->pause - idle;
+ if (idle > HZ)
+ idle = HZ;
+ schedule_timeout_idle(idle);
}
}
@@ -2113,7 +2128,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
struct wc_memory_superblock s;
static struct dm_arg _args[] = {
- {0, 17, "Invalid number of feature args"},
+ {0, 18, "Invalid number of feature args"},
};
as.argc = argc;
@@ -2206,6 +2221,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
goto bad;
}
} else {
+ wc->pause = PAUSE_WRITEBACK;
r = mempool_init_kmalloc_pool(&wc->copy_pool, 1, sizeof(struct copy_struct));
if (r) {
ti->error = "Could not allocate mempool";
@@ -2344,6 +2360,18 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
} else goto invalid_optional;
} else if (!strcasecmp(string, "metadata_only")) {
wc->metadata_only = true;
+ } else if (!strcasecmp(string, "pause_writeback") && opt_params >= 1) {
+ unsigned pause_msecs;
+ if (WC_MODE_PMEM(wc))
+ goto invalid_optional;
+ string = dm_shift_arg(&as), opt_params--;
+ if (sscanf(string, "%u%c", &pause_msecs, &dummy) != 1)
+ goto invalid_optional;
+ if (pause_msecs > 60000)
+ goto invalid_optional;
+ wc->pause = msecs_to_jiffies(pause_msecs);
+ wc->pause_set = true;
+ wc->pause_value = pause_msecs;
} else {
invalid_optional:
r = -EINVAL;
@@ -2569,6 +2597,8 @@ static void writecache_status(struct dm_target *ti, status_type_t type,
extra_args++;
if (wc->metadata_only)
extra_args++;
+ if (wc->pause_set)
+ extra_args += 2;
DMEMIT("%u", extra_args);
if (wc->start_sector_set)
@@ -2591,6 +2621,8 @@ static void writecache_status(struct dm_target *ti, status_type_t type,
DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
if (wc->metadata_only)
DMEMIT(" metadata_only");
+ if (wc->pause_set)
+ DMEMIT(" pause_writeback %u", wc->pause_value);
break;
}
}