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kmem slab fixes 

- spl_slab_reclaim() 'continue' changed back to 'break' from commit
  37db7d8cf9.  The original was correct,
  I have added a comment to ensure this does not happen again.
- spl_slab_reclaim() further optimized by moving the destructor call
  in spl_slab_free() outside the skc->skc_lock.  This minimizes the
  length of time the spin lock is held, allows the destructors to
  be invoked concurrently for different objects, and as a bonus makes
  it safe (although unwise) to sleep in the destructors.
This commit is contained in:
Brian Behlendorf 2009-02-13 10:28:55 -08:00
parent fce5ef8306
commit 1a944a7d0b
1 changed files with 36 additions and 36 deletions
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72
module/spl/spl-kmem.c
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@ -823,7 +823,6 @@ spl_slab_free(spl_kmem_slab_t *sks,
struct list_head *sks_list, struct list_head *sko_list)
{
spl_kmem_cache_t *skc;
spl_kmem_obj_t *sko, *n;
ENTRY;
ASSERT(sks->sks_magic == SKS_MAGIC);
@ -833,23 +832,18 @@ spl_slab_free(spl_kmem_slab_t *sks,
ASSERT(skc->skc_magic == SKC_MAGIC);
ASSERT(spin_is_locked(&skc->skc_lock));
/*
* Update slab/objects counters in the cache, then remove the
* slab from the skc->skc_partial_list. Finally add the slab
* and all its objects in to the private work lists where the
* destructors will be called and the memory freed to the system.
*/
skc->skc_obj_total -= sks->sks_objs;
skc->skc_slab_total--;
list_del(&sks->sks_list);
/* Run destructors slab is being released */
list_for_each_entry_safe(sko, n, &sks->sks_free_list, sko_list) {
ASSERT(sko->sko_magic == SKO_MAGIC);
list_del(&sko->sko_list);
if (skc->skc_dtor)
skc->skc_dtor(sko->sko_addr, skc->skc_private);
if (skc->skc_flags & KMC_OFFSLAB)
list_add(&sko->sko_list, sko_list);
}
list_add(&sks->sks_list, sks_list);
list_splice_init(&sks->sks_free_list, sko_list);
EXIT;
}
@ -868,27 +862,26 @@ spl_slab_reclaim(spl_kmem_cache_t *skc, int count, int flag)
spl_kmem_obj_t *sko, *n;
LIST_HEAD(sks_list);
LIST_HEAD(sko_list);
int size, i = 0;
int size = 0, i = 0;
ENTRY;
/*
* Move empty slabs and objects which have not been touched in
* skc_delay seconds on to private lists to be freed outside
* the spin lock. This delay time is important to avoid
* thrashing however when flag is set the delay will not be
* used. Empty slabs will be at the end of the skc_partial_list.
* the spin lock. This delay time is important to avoid thrashing
* however when flag is set the delay will not be used.
*/
spin_lock(&skc->skc_lock);
list_for_each_entry_safe_reverse(sks, m, &skc->skc_partial_list,
sks_list) {
/* Release at most count slabs */
if (count && i > count)
list_for_each_entry_safe_reverse(sks,m,&skc->skc_partial_list,sks_list){
/*
* All empty slabs are at the end of skc->skc_partial_list,
* therefore once a non-empty slab is found we can stop
* scanning. Additionally, stop when reaching the target
* reclaim 'count' if a non-zero threshhold is given.
*/
if ((sks->sks_ref > 0) || (count && i > count))
break;
/* Skip active slabs */
if (sks->sks_ref > 0)
continue;
if (time_after(jiffies,sks->sks_age+skc->skc_delay*HZ)||flag) {
spl_slab_free(sks, &sks_list, &sko_list);
i++;
@ -897,24 +890,31 @@ spl_slab_reclaim(spl_kmem_cache_t *skc, int count, int flag)
spin_unlock(&skc->skc_lock);
/*
* We only have list of spl_kmem_obj_t's if they are located off
* the slab, otherwise they get feed with the spl_kmem_slab_t.
* The following two loops ensure all the object destructors are
* run, any offslab objects are freed, and the slabs themselves
* are freed. This is all done outside the skc->skc_lock since
* this allows the destructor to sleep, and allows us to perform
* a conditional reschedule when a freeing a large number of
* objects and slabs back to the system.
*/
if (!list_empty(&sko_list)) {
ASSERT(skc->skc_flags & KMC_OFFSLAB);
if (skc->skc_flags & KMC_OFFSLAB)
size = P2ROUNDUP(skc->skc_obj_size, skc->skc_obj_align) +
P2ROUNDUP(sizeof(spl_kmem_obj_t), skc->skc_obj_align);
/* To avoid soft lockups conditionally reschedule */
list_for_each_entry_safe(sko, n, &sko_list, sko_list) {
list_for_each_entry_safe(sko, n, &sko_list, sko_list) {
ASSERT(sko->sko_magic == SKO_MAGIC);
if (skc->skc_dtor)
skc->skc_dtor(sko->sko_addr, skc->skc_private);
if (skc->skc_flags & KMC_OFFSLAB)
kv_free(skc, sko->sko_addr, size);
cond_resched();
}
cond_resched();
}
/* To avoid soft lockups conditionally reschedule */
list_for_each_entry_safe(sks, m, &sks_list, sks_list) {
ASSERT(sks->sks_magic == SKS_MAGIC);
kv_free(skc, sks, skc->skc_slab_size);
cond_resched();
}