ARC "pressured out", how to control/stabilize ? (reformatted to text/plain)

[Andriy Gapon]

on 14/01/2014 07:27 Vladimir Sharun said the following:
> Dear Andriy and FreeBSD community,
> 
>> I am not sure if the buffers are leaked somehow or if they are actually in use.
>> It's one of the very few places where data buffers are allocated without
>> charging ARC.  In all other places it's quite easy to match allocations and
>> deallocations.  But in L2ARC it is not obvious that all buffers get freed or
>> when that happens.
> 
> After one week under load I think we figure out the cause: it's L2ARC. 
> Here's the top's header for 7d17h of the runtime:
> 
> last pid: 46409;  load averages:  0.37,  0.62,  0.70 up 7+17:14:01  07:24:10
> 173 processes: 1 running, 171 sleeping, 1 zombie
> CPU:  2.0% user,  0.0% nice,  3.5% system,  0.4% interrupt, 94.2% idle
> Mem: 8714M Active, 14G Inact, 96G Wired, 1929M Cache, 3309M Buf, 3542M Free
> ARC: 85G Total, 2558M MFU, 77G MRU, 28M Anon, 1446M Header, 4802M Other
> 
> ARC related tunables:
> 
> vm.kmem_size="110G"
> vfs.zfs.arc_max="90G"
> vfs.zfs.arc_min="42G"
> 
> For more than 7 days of hard runtime the picture clearly shows: 
> Wired minus ARC = 11..12Gb, ARC grow and shrinks in 80-87Gb range and the
> system runs just fine.
> 
> So what shall we do with L2ARC leakage ?


Could you please try this patch
http://cr.illumos.org/~webrev/skiselkov/3995/illumos-gate.patch ?

-- 
Andriy Gapon