Merge #154

154: DLPX-66534 arc_prune consumes all cpus r=grwilson a=grwilson



Co-authored-by: George Wilson <george.wilson@delphix.com>

Author: bors[bot]

files/common/etc/modprobe.d/10-zfs.conf

@@ -82,3 +82,18 @@ options zfs zfs_mg_noalloc_threshold=5
 # Overriding the property here fixes that.
 #
 options zfs zfs_override_estimate_recordsize=8192
+
+#
+# The default arc metadata eviction policy is a balanced policy. This policy
+# evicts both data and metadata and provides a callback to the ZPL layer
+# to evict blocks from the inode and dentry caches. This policy has serious
+# implications because it tries too hard to reduce metadata so that it's
+# below the arc_meta_limit. As a result this can end up consuming all of
+# the cpus and causing the system to run out of memory. Since the arc
+# metadata eviction is called in the critical path, we want a lightweight
+# policy to be used to ensure that eviction happens quickly and new additions
+# to the arc are not blocked for a significant amount of time. To do this,
+# we changes the metadata eviction policy to ARC_STRATEGY_META_ONLY,
+# which is what we used in illumos.
+#
+options zfs zfs_arc_meta_strategy=0