The patch titled
md: allow parallel resync of md-devices.
has been added to the -mm tree. Its filename is
md-allow-parallel-resync-of-md-devices.patch
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------------------------------------------------------
Subject: md: allow parallel resync of md-devices.
From: Bernd Schubert <bs@xxxxxxxxx>
In some configurations, a raid6 resync can be limited by CPU speed
(Calculating P and Q and moving data) rather than by device speed. In
these cases there is nothing to be gained byt serialising resync of arrays
that share a device, and doing the resync in parallel can provide benefit.
So add a sysfs tunable to flag an array as being allowed to resync in
parallel with other arrays that use (a different part of) the same device.
Signed-off-by: Bernd Schubert <bs@xxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/md/md.c | 40 ++++++++++++++++++++++++++++++++----
include/linux/raid/md_k.h | 3 ++
2 files changed, 39 insertions(+), 4 deletions(-)
diff -puN drivers/md/md.c~md-allow-parallel-resync-of-md-devices drivers/md/md.c
--- a/drivers/md/md.c~md-allow-parallel-resync-of-md-devices
+++ a/drivers/md/md.c
@@ -74,6 +74,8 @@ static DEFINE_SPINLOCK(pers_lock);
static void md_print_devices(void);
+static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
+
#define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); }
/*
@@ -3013,6 +3015,36 @@ degraded_show(mddev_t *mddev, char *page
static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);
static ssize_t
+sync_force_parallel_show(mddev_t *mddev, char *page)
+{
+ return sprintf(page, "%d\n", mddev->parallel_resync);
+}
+
+static ssize_t
+sync_force_parallel_store(mddev_t *mddev, const char *buf, size_t len)
+{
+ long n;
+
+ if (strict_strtol(buf, 10, &n))
+ return -EINVAL;
+
+ if (n != 0 && n != 1)
+ return -EINVAL;
+
+ mddev->parallel_resync = n;
+
+ if (mddev->sync_thread)
+ wake_up(&resync_wait);
+
+ return len;
+}
+
+/* force parallel resync, even with shared block devices */
+static struct md_sysfs_entry md_sync_force_parallel =
+__ATTR(sync_force_parallel, S_IRUGO|S_IWUSR,
+ sync_force_parallel_show, sync_force_parallel_store);
+
+static ssize_t
sync_speed_show(mddev_t *mddev, char *page)
{
unsigned long resync, dt, db;
@@ -3187,6 +3219,7 @@ static struct attribute *md_redundancy_a
&md_sync_min.attr,
&md_sync_max.attr,
&md_sync_speed.attr,
+ &md_sync_force_parallel.attr,
&md_sync_completed.attr,
&md_max_sync.attr,
&md_suspend_lo.attr,
@@ -5487,8 +5520,6 @@ void md_allow_write(mddev_t *mddev)
}
EXPORT_SYMBOL_GPL(md_allow_write);
-static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
-
#define SYNC_MARKS 10
#define SYNC_MARK_STEP (3*HZ)
void md_do_sync(mddev_t *mddev)
@@ -5552,8 +5583,9 @@ void md_do_sync(mddev_t *mddev)
for_each_mddev(mddev2, tmp) {
if (mddev2 == mddev)
continue;
- if (mddev2->curr_resync &&
- match_mddev_units(mddev,mddev2)) {
+ if (!mddev->parallel_resync
+ && mddev2->curr_resync
+ && match_mddev_units(mddev, mddev2)) {
DEFINE_WAIT(wq);
if (mddev < mddev2 && mddev->curr_resync == 2) {
/* arbitrarily yield */
diff -puN include/linux/raid/md_k.h~md-allow-parallel-resync-of-md-devices include/linux/raid/md_k.h
--- a/include/linux/raid/md_k.h~md-allow-parallel-resync-of-md-devices
+++ a/include/linux/raid/md_k.h
@@ -180,6 +180,9 @@ struct mddev_s
int sync_speed_min;
int sync_speed_max;
+ /* resync even though the same disks are shared among md-devices */
+ int parallel_resync;
+
int ok_start_degraded;
/* recovery/resync flags
* NEEDED: we might need to start a resync/recover
_
Patches currently in -mm which might be from bs@xxxxxxxxx are
md-allow-parallel-resync-of-md-devices.patch
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