Re: Wait events monitoring future development

On Mon, Aug 8, 2016 at 10:03 AM, Bruce Momjian <bruce@momjian.us> wrote:
> On Mon, Aug  8, 2016 at 04:43:40PM +0530, Amit Kapila wrote:
>> >    According to developers, overhead is small, but many people have doubts
>> > that it can be much more significant for intensive workloads. Obviously, it
>> > is not an easy task to test, because you need to put doubtfully
>> > non-production ready code into mission-critical production for such tests.
>> >    As a result it will be clear if this design should be abandoned  and we
>> > need to think about less-invasive solutions or this design is acceptable.
>> >
>>
>> I think here main objection was that gettimeofday can cause
>> performance regression which can be taken care by using configurable
>> knob.  I am not aware if any other part of the design has been
>> discussed in detail to conclude whether it has any obvious problem.
>
> It seems asking users to run pg_test_timing before deploying to check
> the overhead would be sufficient.

They should also run it in parallel, as sometimes the real overhead is
in synchronization between multiple CPUs and doesn't show up when only
a single CPU is involved.

Cheers,

Jeff