Commit 0301dae7 authored by Hans Holmberg's avatar Hans Holmberg Committed by Carlos Maiolino
Browse files

xfs: refactor hint based zone allocation 



Replace the co-location code with a matrix that makes it more clear
on how the decisions are made.

The matrix contains scores for zone/file hint combinations. A "GOOD"
score for an open zone will result in immediate co-location while "OK"
combinations will only be picked if we cannot open a new zone.

Signed-off-by: default avatarHans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarCarlos Maiolino <cem@kernel.org>
parent 94deac97

fs/xfs/xfs_zone_alloc.c

+62 −60
Original line number Diff line number Diff line
@@ -493,64 +493,64 @@ xfs_try_open_zone( 
	return oz;

}



enum xfs_zone_alloc_score {

	/* Any open zone will do it, we're desperate */

	XFS_ZONE_ALLOC_ANY	= 0,



	/* It better fit somehow */

	XFS_ZONE_ALLOC_OK	= 1,



	/* Only reuse a zone if it fits really well. */

	XFS_ZONE_ALLOC_GOOD	= 2,

};



/*

 * For data with short or medium lifetime, try to colocated it into an

 * already open zone with a matching temperature.

 * Life time hint co-location matrix.  Fields not set default to 0

 * aka XFS_ZONE_ALLOC_ANY.

 */

static bool

xfs_colocate_eagerly(

	enum rw_hint		file_hint)

{

	switch (file_hint) {

	case WRITE_LIFE_MEDIUM:

	case WRITE_LIFE_SHORT:

	case WRITE_LIFE_NONE:

		return true;

	default:

		return false;

	}

}



static bool

xfs_good_hint_match(

	struct xfs_open_zone	*oz,

	enum rw_hint		file_hint)

{

	switch (oz->oz_write_hint) {

	case WRITE_LIFE_LONG:

	case WRITE_LIFE_EXTREME:

		/* colocate long and extreme */

		if (file_hint == WRITE_LIFE_LONG ||

		    file_hint == WRITE_LIFE_EXTREME)

			return true;

		break;

	case WRITE_LIFE_MEDIUM:

		/* colocate medium with medium */

		if (file_hint == WRITE_LIFE_MEDIUM)

			return true;

		break;

	case WRITE_LIFE_SHORT:

	case WRITE_LIFE_NONE:

	case WRITE_LIFE_NOT_SET:

		/* colocate short and none */

		if (file_hint <= WRITE_LIFE_SHORT)

			return true;

		break;

	}

	return false;

}

static const unsigned int

xfs_zoned_hint_score[WRITE_LIFE_HINT_NR][WRITE_LIFE_HINT_NR] = {

	[WRITE_LIFE_NOT_SET]	= {

		[WRITE_LIFE_NOT_SET]	= XFS_ZONE_ALLOC_OK,

		[WRITE_LIFE_NONE]	= XFS_ZONE_ALLOC_OK,

		[WRITE_LIFE_SHORT]	= XFS_ZONE_ALLOC_OK,

	},

	[WRITE_LIFE_NONE]	= {

		[WRITE_LIFE_NOT_SET]	= XFS_ZONE_ALLOC_OK,

		[WRITE_LIFE_NONE]	= XFS_ZONE_ALLOC_GOOD,

		[WRITE_LIFE_SHORT]	= XFS_ZONE_ALLOC_GOOD,

	},

	[WRITE_LIFE_SHORT]	= {

		[WRITE_LIFE_NOT_SET]	= XFS_ZONE_ALLOC_GOOD,

		[WRITE_LIFE_NONE]	= XFS_ZONE_ALLOC_GOOD,

		[WRITE_LIFE_SHORT]	= XFS_ZONE_ALLOC_GOOD,

	},

	[WRITE_LIFE_MEDIUM]	= {

		[WRITE_LIFE_MEDIUM]	= XFS_ZONE_ALLOC_GOOD,

	},

	[WRITE_LIFE_LONG]	= {

		[WRITE_LIFE_LONG]	= XFS_ZONE_ALLOC_OK,

		[WRITE_LIFE_EXTREME]	= XFS_ZONE_ALLOC_OK,

	},

	[WRITE_LIFE_EXTREME]	= {

		[WRITE_LIFE_LONG]	= XFS_ZONE_ALLOC_OK,

		[WRITE_LIFE_EXTREME]	= XFS_ZONE_ALLOC_OK,

	},

};



static bool

xfs_try_use_zone(

	struct xfs_zone_info	*zi,

	enum rw_hint		file_hint,

	struct xfs_open_zone	*oz,

	bool			lowspace)

	unsigned int		goodness)

{

	if (oz->oz_allocated == rtg_blocks(oz->oz_rtg))

		return false;

	if (!lowspace && !xfs_good_hint_match(oz, file_hint))



	if (xfs_zoned_hint_score[oz->oz_write_hint][file_hint] < goodness)

		return false;



	if (!atomic_inc_not_zero(&oz->oz_ref))

		return false;
@@ -581,14 +581,14 @@ static struct xfs_open_zone * 
xfs_select_open_zone_lru(

	struct xfs_zone_info	*zi,

	enum rw_hint		file_hint,

	bool			lowspace)

	unsigned int		goodness)

{

	struct xfs_open_zone	*oz;



	lockdep_assert_held(&zi->zi_open_zones_lock);



	list_for_each_entry(oz, &zi->zi_open_zones, oz_entry)

		if (xfs_try_use_zone(zi, file_hint, oz, lowspace))

		if (xfs_try_use_zone(zi, file_hint, oz, goodness))

			return oz;



	cond_resched_lock(&zi->zi_open_zones_lock);
@@ -651,9 +651,11 @@ xfs_select_zone_nowait( 
	 * data.

	 */

	spin_lock(&zi->zi_open_zones_lock);

	if (xfs_colocate_eagerly(write_hint))

		oz = xfs_select_open_zone_lru(zi, write_hint, false);

	else if (pack_tight)

	oz = xfs_select_open_zone_lru(zi, write_hint, XFS_ZONE_ALLOC_GOOD);

	if (oz)

		goto out_unlock;



	if (pack_tight)

		oz = xfs_select_open_zone_mru(zi, write_hint);

	if (oz)

		goto out_unlock;
@@ -667,16 +669,16 @@ xfs_select_zone_nowait( 
		goto out_unlock;



	/*

	 * Try to colocate cold data with other cold data if we failed to open a

	 * new zone for it.

	 * Try to find an zone that is an ok match to colocate data with.

	 */

	oz = xfs_select_open_zone_lru(zi, write_hint, XFS_ZONE_ALLOC_OK);

	if (oz)

		goto out_unlock;



	/*

	 * Pick the least recently used zone, regardless of hint match

	 */

	if (write_hint != WRITE_LIFE_NOT_SET &&

	    !xfs_colocate_eagerly(write_hint))

		oz = xfs_select_open_zone_lru(zi, write_hint, false);

	if (!oz)

		oz = xfs_select_open_zone_lru(zi, WRITE_LIFE_NOT_SET, false);

	if (!oz)

		oz = xfs_select_open_zone_lru(zi, WRITE_LIFE_NOT_SET, true);

	oz = xfs_select_open_zone_lru(zi, write_hint, XFS_ZONE_ALLOC_ANY);

out_unlock:

	spin_unlock(&zi->zi_open_zones_lock);

	return oz;