Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4e781b49 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm cache: speed up writing of the hint array 



It's far quicker to always delete the hint array and recreate with
dm_array_new() because we avoid the copying caused by mutation.

Also simplifies the policy interface, replacing the walk_hints() with
the simpler get_hint().

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent dd6a77d9

drivers/md/dm-cache-metadata.c

+27 −53
Original line number Diff line number Diff line
@@ -1368,10 +1368,24 @@ int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd, 


/*----------------------------------------------------------------*/



static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)

static int get_hint(uint32_t index, void *value_le, void *context)

{

	uint32_t value;

	struct dm_cache_policy *policy = context;



	value = policy_get_hint(policy, to_cblock(index));

	*((__le32 *) value_le) = cpu_to_le32(value);



	return 0;

}



/*

 * It's quicker to always delete the hint array, and recreate with

 * dm_array_new().

 */

static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)

{

	int r;

	__le32 value;

	size_t hint_size;

	const char *policy_name = dm_cache_policy_get_name(policy);

	const unsigned *policy_version = dm_cache_policy_get_version(policy);
@@ -1380,7 +1394,6 @@ static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po 
	    (strlen(policy_name) > sizeof(cmd->policy_name) - 1))

		return -EINVAL;



	if (!policy_unchanged(cmd, policy)) {

	strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));

	memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
@@ -1395,48 +1408,9 @@ static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po 
			return r;

	}



		r = dm_array_empty(&cmd->hint_info, &cmd->hint_root);

		if (r)

			return r;



		value = cpu_to_le32(0);

		__dm_bless_for_disk(&value);

		r = dm_array_resize(&cmd->hint_info, cmd->hint_root, 0,

	return dm_array_new(&cmd->hint_info, &cmd->hint_root,

			    from_cblock(cmd->cache_blocks),

				    &value, &cmd->hint_root);

		if (r)

			return r;

	}



	return 0;

}



static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, uint32_t hint)

{

	struct dm_cache_metadata *cmd = context;

	__le32 value = cpu_to_le32(hint);

	int r;



	__dm_bless_for_disk(&value);



	r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,

			       from_cblock(cblock), &value, &cmd->hint_root);

	cmd->changed = true;



	return r;

}



static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)

{

	int r;



	r = begin_hints(cmd, policy);

	if (r) {

		DMERR("begin_hints failed");

		return r;

	}



	return policy_walk_mappings(policy, save_hint, cmd);

			    get_hint, policy);

}



int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)

drivers/md/dm-cache-policy-cleaner.c

+1 −1
Original line number Diff line number Diff line
@@ -395,7 +395,7 @@ static void init_policy_functions(struct policy *p) 
	p->policy.set_dirty = wb_set_dirty;

	p->policy.clear_dirty = wb_clear_dirty;

	p->policy.load_mapping = wb_load_mapping;

	p->policy.walk_mappings = NULL;

	p->policy.get_hint = NULL;

	p->policy.remove_mapping = wb_remove_mapping;

	p->policy.writeback_work = wb_writeback_work;

	p->policy.force_mapping = wb_force_mapping;

drivers/md/dm-cache-policy-internal.h

+3 −3
Original line number Diff line number Diff line
@@ -48,10 +48,10 @@ static inline int policy_load_mapping(struct dm_cache_policy *p, 
	return p->load_mapping(p, oblock, cblock, hint, hint_valid);

}



static inline int policy_walk_mappings(struct dm_cache_policy *p,

				      policy_walk_fn fn, void *context)

static inline uint32_t policy_get_hint(struct dm_cache_policy *p,

				       dm_cblock_t cblock)

{

	return p->walk_mappings ? p->walk_mappings(p, fn, context) : 0;

	return p->get_hint ? p->get_hint(p, cblock) : 0;

}



static inline int policy_writeback_work(struct dm_cache_policy *p,

drivers/md/dm-cache-policy-smq.c

+6 −32
Original line number Diff line number Diff line
@@ -1375,41 +1375,15 @@ static int smq_load_mapping(struct dm_cache_policy *p, 
	return 0;

}



static int smq_save_hints(struct smq_policy *mq, struct queue *q,

			  policy_walk_fn fn, void *context)

{

	int r;

	unsigned level;

	struct entry *e;



	for (level = 0; level < q->nr_levels; level++)

		for (e = l_head(q->es, q->qs + level); e; e = l_next(q->es, e)) {

			if (!e->sentinel) {

				r = fn(context, infer_cblock(mq, e),

				       e->oblock, e->level);

				if (r)

					return r;

			}

		}



	return 0;

}



static int smq_walk_mappings(struct dm_cache_policy *p, policy_walk_fn fn,

			     void *context)

static uint32_t smq_get_hint(struct dm_cache_policy *p, dm_cblock_t cblock)

{

	struct smq_policy *mq = to_smq_policy(p);

	int r = 0;

	struct entry *e = get_entry(&mq->cache_alloc, from_cblock(cblock));



	/*

	 * We don't need to lock here since this method is only called once

	 * the IO has stopped.

	 */

	r = smq_save_hints(mq, &mq->clean, fn, context);

	if (!r)

		r = smq_save_hints(mq, &mq->dirty, fn, context);

	if (!e->allocated)

		return 0;



	return r;

	return e->level;

}



static void __remove_mapping(struct smq_policy *mq, dm_oblock_t oblock)
@@ -1616,7 +1590,7 @@ static void init_policy_functions(struct smq_policy *mq, bool mimic_mq) 
	mq->policy.set_dirty = smq_set_dirty;

	mq->policy.clear_dirty = smq_clear_dirty;

	mq->policy.load_mapping = smq_load_mapping;

	mq->policy.walk_mappings = smq_walk_mappings;

	mq->policy.get_hint = smq_get_hint;

	mq->policy.remove_mapping = smq_remove_mapping;

	mq->policy.remove_cblock = smq_remove_cblock;

	mq->policy.writeback_work = smq_writeback_work;

drivers/md/dm-cache-policy.h

+5 −5
Original line number Diff line number Diff line
@@ -90,9 +90,6 @@ struct policy_result { 
	dm_cblock_t cblock;	/* POLICY_HIT, POLICY_NEW, POLICY_REPLACE */

};



typedef int (*policy_walk_fn)(void *context, dm_cblock_t cblock,

			      dm_oblock_t oblock, uint32_t hint);



/*

 * The cache policy object.  Just a bunch of methods.  It is envisaged that

 * this structure will be embedded in a bigger, policy specific structure
@@ -158,8 +155,11 @@ struct dm_cache_policy { 
	int (*load_mapping)(struct dm_cache_policy *p, dm_oblock_t oblock,

			    dm_cblock_t cblock, uint32_t hint, bool hint_valid);



	int (*walk_mappings)(struct dm_cache_policy *p, policy_walk_fn fn,

			     void *context);

	/*

	 * Gets the hint for a given cblock.  Called in a single threaded

	 * context.  So no locking required.

	 */

	uint32_t (*get_hint)(struct dm_cache_policy *p, dm_cblock_t cblock);



	/*

	 * Override functions used on the error paths of the core target.