Re: r273165. ZFS ARC: possible memory leak to Inact

On 05/11/2014 06:15, Marcus Reid wrote:
> On Tue, Nov 04, 2014 at 06:13:44PM +0000, Steven Hartland wrote:
>> On 04/11/2014 17:22, Allan Jude wrote:
>>> snip...
>>> Justin Gibbs and I were helping George from Voxer look at the same issue
>>> they are having. They had ~169GB in inact, and only ~60GB being used for
>>> ARC.
>>>
>>> Are there any further debugging steps we can recommend to him to help
>>> investigate this?
>> The various scripts attached to the ZS ARC behavior problem and fix PR
>> will help provide detail this.
>> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=187594
>>
>> I've seen it here where there's been bursts of ZFS I/O specifically
>> write bursts.
>>
>> What happens is that ZFS will consume large amounts of space in various
>> UMA zones to accommodate these bursts.
> If you push the vmstat -z that he provided through the arc summary
> script, you'll see that this is not what is happening.  His uma stats
> match up with his arc, and do not account for his inactive memory.
>
> uma script summary:
>
>      Totals
>      oused: 5.860GB, ofree: 1.547GB, ototal: 7.407GB
>      zused: 56.166GB, zfree: 3.918GB, ztotal: 60.084GB
>      used: 62.026GB, free: 5.465GB, total: 67.491GB
>
> His provided top stats:
>
>      Mem: 19G Active, 20G Inact, 81G Wired, 59M Cache, 3308M Buf, 4918M Free
>      ARC: 66G Total, 6926M MFU, 54G MRU, 8069K Anon, 899M Header, 5129M Other
>
>
> The big uma buckets (zio_buf_16384 and zio_data_buf_131072, 18.002GB and
> 28.802GB respectively) are nearly 0% free.
>
Still potentially accounts for 5.4GB of your 20GB inact.

The rest could be malloc backed allocations?

     Regards
     Steve