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Do not ignore arc_adjust() return value.

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This covers scenario when ARC may not shrink as fast as it could:
1. arc_size < arc_c and arc_adjust() does not evict anything, returning
   zero to arc_reclaim_thread();
2. arc_available_memory() reports memory pressure, which can not be
   satisfied by arc_kmem_reap_now();
3. arc_shrink() reduces arc_c and calls arc_adjust(), return of which is
   ignored;
4. even if the last arc_adjust() could not satisfy arc_size < arc_c,
   arc_reclaim_thread() will still go to sleep, since the first one
   returned zero.

Reviewed by:	allanjude, markj, sef
MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
Differential Revision:	https://reviews.freebsd.org/D17927
This commit is contained in:
mav 2018-11-10 01:58:37 +00:00
parent 7f7d4fc5f9
commit 7ddbc411f2
1 changed files with 4 additions and 3 deletions
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7
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
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@ -4565,7 +4565,7 @@ arc_flush(spa_t *spa, boolean_t retry)
(void) arc_flush_state(arc_mfu_ghost, guid, ARC_BUFC_METADATA, retry);
}
void
uint64_t
arc_shrink(int64_t to_free)
{
uint64_t asize = aggsum_value(&arc_size);
@ -4593,8 +4593,9 @@ arc_shrink(int64_t to_free)
if (asize > arc_c) {
DTRACE_PROBE2(arc__shrink_adjust, uint64_t, asize,
uint64_t, arc_c);
(void) arc_adjust();
return (arc_adjust());
}
return (0);
}
typedef enum free_memory_reason_t {
@ -4917,7 +4918,7 @@ arc_reclaim_thread(void *unused __unused)
to_free = MAX(to_free, ptob(needfree));
#endif
#endif
arc_shrink(to_free);
evicted += arc_shrink(to_free);
}
} else if (free_memory < arc_c >> arc_no_grow_shift) {
arc_no_grow = B_TRUE;