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dm cache: speed up writing of the hint array

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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: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2016-09-15 09:23:46 -04:00 committed by Mike Snitzer
parent dd6a77d998
commit 4e781b498e
5 changed files with 42 additions and 94 deletions
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80
drivers/md/dm-cache-metadata.c
View File

@ -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);
@ -1380,63 +1394,23 @@ 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));
strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
hint_size = dm_cache_policy_get_hint_size(policy);
if (!hint_size)
return 0; /* short-circuit hints initialization */
cmd->policy_hint_size = hint_size;
hint_size = dm_cache_policy_get_hint_size(policy);
if (!hint_size)
return 0; /* short-circuit hints initialization */
cmd->policy_hint_size = hint_size;
if (cmd->hint_root) {
r = dm_array_del(&cmd->hint_info, cmd->hint_root);
if (r)
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,
from_cblock(cmd->cache_blocks),
&value, &cmd->hint_root);
if (cmd->hint_root) {
r = dm_array_del(&cmd->hint_info, 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);
return dm_array_new(&cmd->hint_info, &cmd->hint_root,
from_cblock(cmd->cache_blocks),
get_hint, policy);
}
int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)

2
drivers/md/dm-cache-policy-cleaner.c
View File

@ -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;

6
drivers/md/dm-cache-policy-internal.h
View File

@ -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,

38
drivers/md/dm-cache-policy-smq.c
View File

@ -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;

10
drivers/md/dm-cache-policy.h
View File

@ -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.