8.0-R-p2 ZFS: unixbench causing kmem exhaustion panic
doug at polands.org
Wed Jan 13 17:31:47 UTC 2010
I'm trying to get an 8.0-RELEASE-p2 amd64 box to not crash when
running benchmarks/unixbench. The box in question has 4GB RAM running
6 SCSI disks in a RAID1Z.
dmesg | grep memory
real memory = 4294967296 (4096 MB)
avail memory = 3961372672 (3777 MB)
scrub: none requested
NAME STATE READ WRITE CKSUM
bethesda ONLINE 0 0 0
raidz1 ONLINE 0 0 0
gpt/disk0 ONLINE 0 0 0
gpt/disk1 ONLINE 0 0 0
gpt/disk2 ONLINE 0 0 0
gpt/disk3 ONLINE 0 0 0
gpt/disk4 ONLINE 0 0 0
gpt/disk5 ONLINE 0 0 0
It appears unixbench causes the mem exhaustion when running the fstime
/ fsbuffer / fsdisk programs, depending on what I've got in
I began with a system with no tunables in /boot/loader.conf
(vm.kmem_size and vm.kmem_size_max). Then I tried increasing
vm.kmem_size and vm.kmem_size_max a GB at a time, until I was at 4GB.
At every increase, the system panicked with a kmem exhaustion, until I
used the 4GB settings. At that time, the system system became
unresponsive and had to be reset.
So the question is, can ZFS be tuned to not panic or hang no matter
what I throw at it? In this case, it's the ancient and innocuous
This is a test box right now and I'm more than willing to try various
tests or tweaks to get 8.x FreeBSD/ZFS into a stable state.
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