Debugged this a little more. It appears that the entries that can be reaped
are not at the LRU position (head) of the L1 queue. So those can be free'd
later by lru_run(). I don't see it happening either for some reason.
(gdb) p LRU[1].L1
$29 = {q = {next = 0x7fb459e71960, prev = 0x7fb3ec3c0d30}, id =
LRU_ENTRY_L1, size = 260379}
head of the list is an entry with refcnt 2; but there are several entries
with refcnt 1.
(gdb) p *(mdcache_lru_t *)0x7fb459e71960
$30 = {q = {next = 0x7fb43ddea8a0, prev = 0x7d68a0 <LRU+224>}, qid =
LRU_ENTRY_L1, refcnt = 2, flags = 0, lane = 1, cf = 2}
(gdb) p *(mdcache_lru_t *)0x7fb43ddea8a0
$31 = {q = {next = 0x7fb3f041f9a0, prev = 0x7fb459e71960}, qid =
LRU_ENTRY_L1, refcnt = 1, flags = 0, lane = 1, cf = 0}
(gdb) p *(mdcache_lru_t *)0x7fb3f041f9a0
$32 = {q = {next = 0x7fb466960200, prev = 0x7fb43ddea8a0}, qid =
LRU_ENTRY_L1, refcnt = 1, flags = 0, lane = 1, cf = 0}
(gdb) p *(mdcache_lru_t *)0x7fb466960200
$33 = {q = {next = 0x7fb451e20570, prev = 0x7fb3f041f9a0}, qid =
LRU_ENTRY_L1, refcnt = 2, flags = 0, lane = 1, cf = 1}
The entries with refcnt 1 are moved to L2 by the background thread
(lru_run). However it does it only of the open file count is greater than
low water mark. In my case, the open_fd_count is not high; so lru_run()
doesn't call lru_run_lane() to demote those entries to L2. What is the best
approach to handle this scenario?
Thanks,
Pradeep
On Mon, Aug 7, 2017 at 6:08 AM, Daniel Gryniewicz <d...@redhat.com> wrote:
> It never has been. In cache_inode, a pin-ref kept it from being
> reaped, now any ref beyond 1 keeps it.
>
> On Fri, Aug 4, 2017 at 1:31 PM, Frank Filz <ffilz...@mindspring.com>
> wrote:
> >> 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
> >
> > The refcount 2 prevents reaping.
> >
> > There could be a refcount leak.
> >
> > Hmm, though, I thought the entries_hwmark was a hard limit, guess not...
> >
> > Frank
> >
> >> 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?
> >>
> >> Thanks,
> >> Pradeep
> >>
> >>
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