Commit 90b08710 authored by Bernd Schubert's avatar Bernd Schubert Committed by Linus Torvalds
Browse files

md: allow parallel resync of md-devices. 



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: default avatarBernd Schubert <bs@q-leap.de>
Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4f54b0e9

drivers/md/md.c

+36 −4
Original line number Diff line number Diff line
@@ -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(); }



/*
@@ -3012,6 +3014,36 @@ 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)

{
@@ -3187,6 +3219,7 @@ static struct attribute *md_redundancy_attrs[] = { 
	&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 */

include/linux/raid/md_k.h

+3 −0
Original line number Diff line number Diff line
@@ -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

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