Date: Thu, 13 Sep 2018 10:11:26 -0500 From: Eric van Gyzen <eric@vangyzen.net> To: freebsd-current <freebsd-current@freebsd.org>, markj@FreeBSD.org Subject: Re: arc_reclaim_thread running hot Message-ID: <064f770e-e035-d3a3-c138-54e3f667a9be@vangyzen.net> In-Reply-To: <0cdba37f-6b47-0929-fb72-dcca7e70a05a@vangyzen.net> References: <0cdba37f-6b47-0929-fb72-dcca7e70a05a@vangyzen.net>
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On 9/13/18 8:18 AM, Eric van Gyzen wrote:
> This morning, I found the arc_reclaim_thread running hot on my laptop
> running 12.0-ALPHA5 r338572.
>
> vfs.zfs.arc_max="4294967296" <-- 4 GiB
>
> last pid: 13288; load averages: 1.32, 1.26, 1.16
> Mem: 456M Active, 3837M Inact, 743M Laundry, 2563M Wired, 167M Free
> ARC: 1131M Total, 304M MFU, 145M MRU, 1344K Anon, 9116K Header, 671M Other
> 89M Compressed, 361M Uncompressed, 4.03:1 Ratio
>
> 22 root -8 - 0 256K CPU2 2 309:20 99.75%
> zfskern{arc_reclaim_thread}
>
> zfs_arc_meta_strategy is still the default of 1.
>
> I sampled the thread's stacks with
>
> for N in `jot 1000`; do procstat -kk 100101; done | grep 100101
>
> and put the results here:
>
> https://people.freebsd.org/~vangyzen/arc_reclaim_thread_stacks.txt
>
> I'm happy to help debug this. Just let me know what you need.
The thread eventually returned to normal, and I've rebooted the system
since then, so I no longer have any state. The thread started running
hot at 03:00, so maybe the daily periodic run triggered it. I have to
work now, but I'll try running the periodic stuff manually when I have time.
Eric
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