Date: Sun, 01 Dec 2019 12:52:53 +0100 From: "Peter Much" <pmc@citylink.dinoex.sub.org> To: freebsd-fs@FreeBSD.ORG Subject: ZFS overgrowing arc_max -> OOM kills Message-ID: <op.0b4bafvnio2kyh@localhost>
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Hi all, I thought this matter was solved a long time ago! In fact, I am using ZFS almost from the beginning, and I never observed it seriousely overgrowing ArcMax, until now (this is 11.3-RELEASE-p3). > System Memory: > 9.38% 187.32 MiB Active, 0.37% 7.35 MiB Inact > 78.60% 1.53 GiB Wired, 0.00% 0 Cache > 1.11% 22.14 MiB Free, 10.54% 210.59 MiB Gap > Real Installed: 2.00 GiB > Real Available: 99.19% 1.98 GiB > Real Managed: 98.33% 1.95 GiB > Logical Total: 2.00 GiB > Logical Used: 98.56% 1.97 GiB > Logical Free: 1.44% 29.49 MiB > Kernel Memory: 768.84 MiB > Data: 98.21% 755.05 MiB > Text: 1.79% 13.79 MiB > Kernel Memory Map: 1.38 GiB > Size: 98.79% 1.36 GiB > Free: 1.21% 17.10 MiB See the KMEM! Obviousely, this was the last useful vital sign from the machine, then it stalled normal I/O and did only network gatewaying: > last pid: 51252; load averages: 0.39, 3.09, 3.68 up 5+07:46:39 > 03:09:25 > 1569 processes: 3 running, 1530 sleeping, 36 waiting > CPU 0: 1.1% user, 0.0% nice, 5.0% system, 0.4% interrupt, 93.5% idle > CPU 1: 0.0% user, 0.0% nice, 3.4% system, 1.9% interrupt, 94.6% idle > Mem: 169M Active, 4K Inact, 204M Laundry, 1582M Wired, 85M Buf, 43M Free > ARC: 1026M Total, 483M MFU, 160M MRU, 11M Anon, 188M Header, 184M Other > 127M Compressed, 526M Uncompressed, 4.16:1 Ratio > Swap: 8192M Total, 1965M Used, 6227M Free, 23% Inuse, 56K In Now see the ARC: > ARC Summary: (HEALTHY) > Memory Throttle Count: 0 > ARC Misc: > Deleted: 22.35m > Recycle Misses: 0 > Mutex Misses: 22.11m > Evict Skips: 733.63m > ARC Size: 127.01% 1016.06 MiB > Target Size: (Adaptive) 25.00% 200.00 MiB > Min Size (Hard Limit): 25.00% 200.00 MiB > Max Size (High Water): 4:1 800.00 MiB This was steadily growing since 03:01 - likely due to the influx of metadata from these daily/security/100/110 "find" jobs. I did my calculations to cater for a 25% safety margin (which appear to be quite accurate), but nevertheless, ZFS goes beyond that. :( (Yes, this is i386 - it's a twenty-year-old machine. ;)) The problem started with OOM kills at 03:02 reporting "out of swap", which is bogus (there is no swap shortage); so I found a way to switch such annoying behaviour off: > vm.pageout_oom_seq=512 Then, instead, I got massive "indefinite buffer wait" messages. And these seem to come from what You can read above: out of kernel heap. PMc
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