autovacuum_naptime seems to take minutes for seconds

Hello,

Concerns: 8.4.2

I cannot test it on other systems than FreeBSD so I don't know whether it's just FreeBSD related.

The parameter autovacuum_naptime seems to take minutes for seconds.

On a completely idle system, no db access, with the default autovacuum_naptime=1min configuration I get:

gamma# iostat -w1 ar1
tty ar1 cpu
tin tout KB/t tps MB/s us ni sy in id
1 234 88.35 10 0.87 0 0 0 0 99
1 129 125.24 29 3.54 0 0 0 0 99
0 44 125.71 14 1.72 0 0 0 0 99
0 44 121.47 30 3.55 0 0 1 0 99
0 44 125.71 14 1.72 1 0 0 0 99
0 44 125.24 29 3.54 0 0 1 0 99
0 44 124.69 29 3.53 0 0 1 0 99
0 44 126.29 28 3.45 0 0 0 0 100
0 45 118.13 15 1.73 1 0 0 0 99
0 44 121.47 30 3.55 1 0 1 0 98
0 44 43.65 102 4.34 0 0 1 0 99
0 43 125.24 29 3.54 0 0 1 0 99
0 44 125.71 14 1.72 0 0 0 0 99
0 44 117.29 31 3.55 0 0 1 0 99
6 44 124.69 29 3.53 0 0 0 0 100
31 45 125.71 14 1.72 0 0 0 0 99

with autovacuum_naptime=5min

gamma# iostat -w1 ar1
tty ar1 cpu
tin tout KB/t tps MB/s us ni sy in id
1 231 88.42 10 0.87 0 0 0 0 99
1 129 117.94 31 3.56 0 0 1 0 99
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 119.20 30 3.49 0 0 0 0 99
0 44 0.00 0 0.00 0 0 0 0 99
0 43 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 117.94 31 3.57 0 0 1 0 99
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 119.20 30 3.49 0 0 1 0 99
0 44 0.00 0 0.00 0 0 0 0 100

with autovacuum_naptime=60min I get the default expected result of a minute:

gamma# iostat -w1 ar1
tty ar1 cpu
tin tout KB/t tps MB/s us ni sy in id
1 229 88.42 10 0.87 0 0 0 0 99
1 129 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 2.00 2 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 4.00 1 0.00 0 0 0 0 100
0 44 16.00 1 0.02 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 16.00 13 0.20 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 2.00 1 0.00 0 0 0 0 100
0 44 7.43 7 0.05 0 0 0 0 99
0 43 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
tty ar1 cpu
tin tout KB/t tps MB/s us ni sy in id
0 44 0.00 0 0.00 0 0 0 0 100
0 130 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 124.69 29 3.53 0 0 1 0 99
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
tty ar1 cpu
tin tout KB/t tps MB/s us ni sy in id
0 44 16.00 11 0.17 0 0 0 0 100
0 130 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 20.75 8 0.16 0 0 1 0 99
0 43 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100
0 44 0.00 0 0.00 0 0 0 0 100

Ragards

Claudio
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