Seeing this behaviour on 10.1-RELEASE and 10.1-STABLE (May 26th) amd64 systems. Systems are low-memory (2GB), but have also seen this behaviour on high (256GB) memory systems all without swap. 10.0-RELEASE seems to NOT be affected. How-to-repeat: Run a system without swap and a ZFS filesystem (eg: 1TB to 2TB used). Appears to be triggered when deleting (either through snapshots, or via regular files) a large of amount data (hundreds of GB) (even with few files). Wired memory skyrockets and is never reclaimed until hitting vm.v_free_min, after which the kernel randomly kills processes to stay up. Once this has been done, sometimes the wired memory is reclaimed, sometimes not. Exactly the same config on 10.0-RELEASE is not affected. Have tried setting: vfs.zfs.arc_max=128M (and lower) vfs.zfs.zio.use_uma=0 (no effect) increasing v_free_min and v_free_target = system just kills processes faster
my test case on 10.2-RELEASE amd64 1. create 1G file # dd if=/dev/urandom bs=1024 count=1024 of=blockout.bin 2. while : ; do cat blockout.bin ; done | pv -brt | dd bs=1024k count=16000 of=blockout2.bin 3. see Wired and ARC counts on 'top' output 4. remove blockout2.bin 5. see Wired and ARC counts on 'top' output my solution: disable UMA for ZFS vfs.zfs.zio.use_uma="0" vfs.zfs.arc_max="16G" try it