Hey Przemek,
1. Since you're not seeing any contention probes fire, it's not
surprising that you never (rarely) see output from plockstat.
2. I've confirmed with an Oracle user that the database indeed rolls
its own locking primitives.
3. I imagine that the lock events that you're seeing are internal to
various libraries. You can confirm this by running the following
script:
dtrace -p <pid> -n 'plockstat$target:::{ @[probename, ustack()] = count(); }'
ADam
2011/8/10 <przemol...@poczta.fm>:
> Hi Adam,
>
> thank you for you answer.
> The behaviour I had described is random: once a 30 dtraces I get some result.
> I also did your test:
>
> # time dtrace -p 23390 -n 'plockstat$target:::{ @[probename] = count(); }'
> dtrace: description 'plockstat$target:::' matched 49 probes
> dtrace: pid 23390 has exited
>
> rw-acquire 19
> rw-release 19
> mutex-acquire 114884
> mutex-release 114884
>
> real 53m37.896s
> user 0m7.684s
> sys 0m16.986s
>
> It seems that Oracle is using built-in locking primitives.
>
> Regards
> Przemek
>
>
> On Tue, Aug 09, 2011 at 09:01:59AM -0700, Adam Leventhal wrote:
>> Hi Przemyslaw,
>>
>> It may be that the Oracle process doesn't use built-in locking
>> primitives. You can test that theory by doing this:
>>
>> # dtrace -p <pid> -n 'plockstat$target:::{ @[probename] = count(); }'
>> <wait for a bit and hit ^C>
>>
>> This will show you the raw plockstat probes that fired. If you see no
>> output, that indicates that Oracle isn't using the core locking
>> primitives in which case you'll need to craft your own scripts for
>> monitoring their locks.
>>
>> Adam
>>
>> On Tue, Aug 9, 2011 at 1:37 AM, <przemol...@poczta.fm> wrote:
>> > Hello,
>> >
>> > I am trying to plockstat on some cpu intensive Oracle processes but get no
>> > result:
>> > # plockstat -x dynvarsize=50m -x aggsize=50m -A -n 5 -p 26602
>> > 0
>> >
>> > Does anybody know why ? What sould I change to get some results ?
>> > I have tried different parameters (including bigger dynvarsize/aggsize)
>> > but still no reult.
>> >
>> > (This is Solaris 10 - sorry but there is no other forum for this kind of
>> > questions :-))
>> >
>> >
>> > Regards
>> > Przemyslaw Bak (przemol)
>> >
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Adam Leventhal, Delphix
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