Re: Review: DTrace probes (merged version)

Tom Lane napsal(a):
> Alvaro Herrera <alvherre@commandprompt.com> writes:
>>> Autovacuum_start probe is alone. I propose following probes for completeness:
>>>
>>> proc-autovacuum-start
>>> proc-autovacuum-stop
>>> proc-bgwriter-start
>>> proc-bgwriter-stop
> 
>> Separate proc-autovacuum-worker-start and proc-autovacuum-launcher-start,
>> perhaps.  Not that I see any usefulness in tracking autovacuum launcher
>> start and stop, but then if we're tracking bgwriter start and stop then
>> it makes the same sense.
> 
> I see no value in cluttering the system with useless probes.  The worker
> start/stop are the only ones here with any conceivable application IMHO.

As I answered to Alvaro. I needed to catch start of backend several times to 
track call flow or attach debugger. It is possible to use some other dtrace 
magic for that, but it is not easy and there is not way how to determine what 
kind of process it is.  For example how to measure how many writes performs 
bgwriter?
Zdenek


-- 
Zdenek Kotala              Sun Microsystems
Prague, Czech Republic     http://sun.com/postgresql