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authorChris Dunlop <[email protected]>2015-05-06 09:59:17 +1000
committerBrian Behlendorf <[email protected]>2015-05-08 14:14:35 -0700
commit16fcdea36340c658b4557fd34a74915fd618f7a6 (patch)
tree402c5b7b0a8dae692647fe19950b2d2e3fbe38e0
parent63e3a8616b200dc36fe9d298a466bb5c25b58132 (diff)
arc_evict, arc_evict_ghost: reduce stack usage using kmem_zalloc
With debugging enabled and depending on your kernel config, the size of arc_buf_hdr_t can blow out the stack of arc_evict() and arc_evict_ghost() to greater than 1024 bytes. Let's avoid this. Signed-off-by: Chris Dunlop <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3377
-rw-r--r--module/zfs/arc.c32
1 files changed, 20 insertions, 12 deletions
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 421c81e1c..6975ada62 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -1825,13 +1825,15 @@ arc_evict(arc_state_t *state, uint64_t spa, int64_t bytes, boolean_t recycle,
kmutex_t *hash_lock;
boolean_t have_lock;
void *stolen = NULL;
- arc_buf_hdr_t marker = {{{ 0 }}};
+ arc_buf_hdr_t *marker;
int count = 0;
ASSERT(state == arc_mru || state == arc_mfu);
evicted_state = (state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost;
+ marker = kmem_zalloc(sizeof (arc_buf_hdr_t), KM_SLEEP);
+
top:
mutex_enter(&state->arcs_mtx);
mutex_enter(&evicted_state->arcs_mtx);
@@ -1866,14 +1868,14 @@ top:
* the hot code path, so don't sleep.
*/
if (!recycle && count++ > arc_evict_iterations) {
- list_insert_after(list, ab, &marker);
+ list_insert_after(list, ab, marker);
mutex_exit(&evicted_state->arcs_mtx);
mutex_exit(&state->arcs_mtx);
kpreempt(KPREEMPT_SYNC);
mutex_enter(&state->arcs_mtx);
mutex_enter(&evicted_state->arcs_mtx);
- ab_prev = list_prev(list, &marker);
- list_remove(list, &marker);
+ ab_prev = list_prev(list, marker);
+ list_remove(list, marker);
count = 0;
continue;
}
@@ -1957,6 +1959,8 @@ top:
goto top;
}
+ kmem_free(marker, sizeof (arc_buf_hdr_t));
+
if (bytes_evicted < bytes)
dprintf("only evicted %lld bytes from %x\n",
(longlong_t)bytes_evicted, state->arcs_state);
@@ -1986,7 +1990,7 @@ arc_evict_ghost(arc_state_t *state, uint64_t spa, int64_t bytes,
arc_buf_contents_t type)
{
arc_buf_hdr_t *ab, *ab_prev;
- arc_buf_hdr_t marker;
+ arc_buf_hdr_t *marker;
list_t *list = &state->arcs_list[type];
kmutex_t *hash_lock;
uint64_t bytes_deleted = 0;
@@ -1994,7 +1998,9 @@ arc_evict_ghost(arc_state_t *state, uint64_t spa, int64_t bytes,
int count = 0;
ASSERT(GHOST_STATE(state));
- bzero(&marker, sizeof (marker));
+
+ marker = kmem_zalloc(sizeof (arc_buf_hdr_t), KM_SLEEP);
+
top:
mutex_enter(&state->arcs_mtx);
for (ab = list_tail(list); ab; ab = ab_prev) {
@@ -2020,12 +2026,12 @@ top:
* before reacquiring the lock.
*/
if (count++ > arc_evict_iterations) {
- list_insert_after(list, ab, &marker);
+ list_insert_after(list, ab, marker);
mutex_exit(&state->arcs_mtx);
kpreempt(KPREEMPT_SYNC);
mutex_enter(&state->arcs_mtx);
- ab_prev = list_prev(list, &marker);
- list_remove(list, &marker);
+ ab_prev = list_prev(list, marker);
+ list_remove(list, marker);
count = 0;
continue;
}
@@ -2057,13 +2063,13 @@ top:
* hash lock to become available. Once its
* available, restart from where we left off.
*/
- list_insert_after(list, ab, &marker);
+ list_insert_after(list, ab, marker);
mutex_exit(&state->arcs_mtx);
mutex_enter(hash_lock);
mutex_exit(hash_lock);
mutex_enter(&state->arcs_mtx);
- ab_prev = list_prev(list, &marker);
- list_remove(list, &marker);
+ ab_prev = list_prev(list, marker);
+ list_remove(list, marker);
} else {
bufs_skipped += 1;
}
@@ -2076,6 +2082,8 @@ top:
goto top;
}
+ kmem_free(marker, sizeof (arc_buf_hdr_t));
+
if (bufs_skipped) {
ARCSTAT_INCR(arcstat_mutex_miss, bufs_skipped);
ASSERT(bytes >= 0);