Tom Lane wrote:
> There is some debug output available from the ARC code,
> but I dunno if its output is actually useful ;-). Try
>
>
http://developer.postgresql.org/docs/postgres/runtime-config.html#GUC-DEBUG-SHARED-BUFFERS
"debug_shared_buffers (integer)
Number of seconds between ARC reports. If set greater than zero, emit ARC
statistics to the log every so many seconds. Zero (the default) disables
reporting."
It seems it doesn't really do, what it says. Output is only sent during
query execution, no output is sent when no query is active, so it's really
hard to say what happens to buffers during idle time.
Aside from that I don't believe that the output can answer questions about
the efficiency of bgwriter...
DEBUG: ARC T1target= 194 B1len= 779 T1len= 180 T2len= 820 B2len= 208
DEBUG: ARC total = 99% B1hit= 18% T1hit= 6% T2hit= 75% B2hit= 0%
DEBUG: ARC clean buffers at LRU T1= 180 T2= 820
Anyone?
Regarding current default settings - at this page:
http://developer.postgresql.org/~wieck/vacuum_cost/
Jan, you used different settings for tests here. Can you explain your point
of view?
bgwriter_delay = 50 (now default 200)
bgwriter_percent = 2 (now default 1)
bgwriter_maxpages = 200 (now default 100)
Regards,
Michael Paesold