On 7/14/2015 02:49, Shane Ambler wrote: > On 14/07/2015 03:18, Karl Denninger wrote: > >> The ARC is supposed to auto-size and use all available free memory. The >> problem is that the VM system and ARC system both make assumptions that >> under certain load patterns fight with one another, and when this >> happens and ARC wins the system gets in trouble FAST. The pattern is >> that the system will start to page RSS out rather than evict ARC, ARC >> will fill the freed space, it pages more RSS out..... you see where this >> winds up heading yes? >> > > Something I noticed was that vfs.zfs.arc_free_target is smaller > than vm.v_free_target > > on my desktop with 8GB I get > vfs.zfs.arc_free_target: 14091 > vm.v_free_target: 43195 > > Doesn't that cause arc allocation to trigger swapping leaving space > for arc allocation.... > Yes and no.
On my system with the patch:
vm.v_free_target: 130312
vm.stats.vm.v_free_target: 130312
vfs.zfs.arc_free_target: 86375
and...
[karl@NewFS ~]$ pstat -s
Device 1K-blocks Used Avail Capacity
/dev/mirror/sw.eli 67108860 0 67108860 0%
No swapping :-)
It's not busy right now, but this is what the system looks like at the
moment...
1 users Load 0.22 0.28 0.32 Jul 14 06:57
Mem:KB REAL VIRTUAL VN PAGER SWAP
PAGER
Tot Share Tot Share Free in out
in out
Act 2009856 39980 7884504 92820 937732 count
All 17499k 52212 8727248 381980 pages
Proc: Interrupts
r p d s w Csw Trp Sys Int Sof Flt ioflt 2638 total
2 251 1 9264 3332 3982 1134 181 2174 1134 cow 11
uart0 4
830 zfod
pcm0 17
0.4%Sys 0.1%Intr 0.8%User 0.0%Nice 98.8%Idle ozfod
ehci0 uhci
| | | | | | | | | | %ozfod
uhci1 21
> daefr 508
uhci3 ehci
dtbuf 1612 prcfr 991
cpu0:timer
Namei Name-cache Dir-cache 485859 desvn 3105 totfr 139
mps0 256
Calls hits % hits % 161014 numvn react 43
em0:rx 0
7109 7026 99 121460 frevn pdwak 77
em0:tx 0
459 pdpgs
em0:link
Disks da1 da2 da3 da4 da5 da6 da7 intrn 192
em1:rx 0
KB/t 0.00 11.41 10.84 11.68 11.60 0.00 0.00 21089128 wire 165
em1:tx 0
tps 0 21 24 22 21 0 0 1153712 act
em1:link
MB/s 0.00 0.23 0.25 0.25 0.24 0.00 0.00 1281556 inact 32
cpu1:timer
%busy 0 4 5 5 4 0 0 20372 cache 25
cpu9:timer
916480 free 39
cpu4:timer
buf 32
cpu13:time
22
cpu2:timer
33
cpu11:time
28
cpu3:timer
30
cpu14:time
35
cpu5:timer
37
cpu12:time
71
cpu7:timer
26
cpu10:time
26
cpu6:timer
28
cpu8:timer
48
cpu15:time
Most of that wired memory is in ARC...
------------------------------------------------------------------------
ZFS Subsystem Report Tue Jul 14 07:00:29 2015
------------------------------------------------------------------------
ARC Summary: (HEALTHY)
Memory Throttle Count: 0
ARC Misc:
Deleted: 53.54m
Recycle Misses: 15.12m
Mutex Misses: 6.63k
Evict Skips: 275.51m
ARC Size: 75.59% 16.88 GiB
Target Size: (Adaptive) 75.73% 16.91 GiB
Min Size (Hard Limit): 12.50% 2.79 GiB
Max Size (High Water): 8:1 22.33 GiB
ARC Size Breakdown:
Recently Used Cache Size: 58.52% 9.89 GiB
Frequently Used Cache Size: 41.48% 7.01 GiB
ARC Hash Breakdown:
Elements Max: 1.72m
Elements Current: 58.40% 1.00m
Collisions: 50.07m
Chain Max: 8
Chains: 119.31k
------------------------------------------------------------------------
ARC Efficiency: 2.01b
Cache Hit Ratio: 81.50% 1.64b
Cache Miss Ratio: 18.50% 371.70m
Actual Hit Ratio: 79.46% 1.60b
Data Demand Efficiency: 83.00% 1.60b
Data Prefetch Efficiency: 15.11% 21.33m
CACHE HITS BY CACHE LIST:
Anonymously Used: 1.79% 29.34m
Most Recently Used: 6.36% 104.08m
Most Frequently Used: 91.14% 1.49b
Most Recently Used Ghost: 0.09% 1.40m
Most Frequently Used Ghost: 0.62% 10.17m
CACHE HITS BY DATA TYPE:
Demand Data: 81.12% 1.33b
Prefetch Data: 0.20% 3.22m
Demand Metadata: 16.06% 262.92m
Prefetch Metadata: 2.62% 42.89m
CACHE MISSES BY DATA TYPE:
Demand Data: 73.17% 271.97m
Prefetch Data: 4.87% 18.11m
Demand Metadata: 17.75% 65.97m
Prefetch Metadata: 4.21% 15.65m
------------------------------------------------------------------------
--
Karl Denninger
k...@denninger.net <mailto:k...@denninger.net>
/The Market Ticker/
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