When you create a new entry, you get back a ref with it, that you are
expected to release when you're done. In addition, the hash table has a
ref, so the initial ref of an entry is 2.
Otherwise, you'd have to create it, and immediately get_ref(), which is
still racy.
Daniel
On 08/04/2017 02:09 PM, Pradeep wrote:
My mistake. As you both correctly pointed out, refcnt needs to be 1 for reclaim.
It is initialized with 2. So some must be doing an unref()/put() to make it 1.
On 8/4/17, Daniel Gryniewicz <d...@redhat.com> wrote:
On 08/04/2017 01:14 PM, Pradeep wrote:
Hello,
I'm hitting a case where mdcache keeps growing well beyond the high
water mark. Here is a snapshot of the lru_state:
1 = {entries_hiwat = 100000, entries_used = 2306063, chunks_hiwat =
100000, chunks_used = 16462,
It has grown to 2.3 million entries and each entry is ~1.6K.
I looked at the first entry in lane 0, L1 queue:
(gdb) p LRU[0].L1
$9 = {q = {next = 0x7fad64256f00, prev = 0x7faf21a1bc00}, id =
LRU_ENTRY_L1, size = 254628}
(gdb) p (mdcache_entry_t *)(0x7fad64256f00-1024)
$10 = (mdcache_entry_t *) 0x7fad64256b00
(gdb) p $10->lru
$11 = {q = {next = 0x7fad65ea0f00, prev = 0x7d67c0 <LRU>}, qid =
LRU_ENTRY_L1, refcnt = 2, flags = 0, lane = 0, cf = 0}
(gdb) p $10->fh_hk.inavl
$13 = true
Lane 1:
(gdb) p LRU[1].L1
$18 = {q = {next = 0x7fad625c0300, prev = 0x7faec08c5100}, id =
LRU_ENTRY_L1, size = 253006}
(gdb) p (mdcache_entry_t *)(0x7fad625c0300 - 1024)
$21 = (mdcache_entry_t *) 0x7fad625bff00
(gdb) p $21->lru
$22 = {q = {next = 0x7fad66fce600, prev = 0x7d68a0 <LRU+224>}, qid =
LRU_ENTRY_L1, refcnt = 2, flags = 0, lane = 1, cf = 1}
(gdb) p $21->fh_hk.inavl
$24 = true
As per LRU_ENTRY_RECLAIMABLE(), these entry should be reclaimable. Not
sure why it is not able to claim it. Any ideas?
refcnt == 2 is not reclaimable. Reclaimable is refcnt == 1. It checks
for 2 because it just took a ref. Unless you're actually processing
that lane, and so seeing the ref taken during that processing, refcnt
will be 3 when processing, and it won't be reclaimed.
Daniel
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