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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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38
drivers/md/dm-cache-policy-smq.c
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@@ -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;