Memory leak in ZFS?

[Nik Azam]

Hi all,

For the past few weeks, I noticed that the amount of memory reported in top
(sum of active, inact, wired, cache buf and free) keeps decreasing as the
uptime increases. I can't pinpoint to when I first noticed this, as I have
updated the system a few times just in case this has been fixed.

The box has 8GB of RAM, running 8.2-PRERELEASE r216693. The ZFS pool
consists of two RAIDZ1 with 5 disks each and 50GB L2 ARC. Root filesystem is
on UFS on separate disk. I have samba, netatalk, istgt, mysql and apache
running on the box.

After booting up, top reports I have 8GB of memory as expected. After moving
files around in the ZFS pool, the ARC grows to 4GB (the maximum size I set).
Now the box has been up for 10 days, and the sum of memory reported in top
is about 4GB (3GB wired). ARC size is about 2GB. I tried stopping all the
services running, but this didn't help. When unmounting the ZFS pool (via
/etc/rc.d/zfs stop), top reports that I have 8GB again. Throughout the 10
days period, there is no user activity at all to the UFS filesystem.

Is there anything sinister happening here? Or is it just top is playing
tricks on me?

Thanks,
Nik