Re: [PATCH v3 1/1] fetch: add trace2 instrumentation

> On 11/7/2019 12:32 AM, Junio C Hamano wrote:
>> So this introduces a single region around the entire function body
>> of mark_complete_and_common_ref(), within which only one subpart is
>> also enclosed in a nested region.  Is that because the parts inside
>> the outer region before and after the inner region are known to
>> consume negligible time?  IOW I would understand
>> 
>>         F () {
>> ...
>>         }
>> 
>> or
>> 
>>         F () {
>>                         trivial code
>>                 <region 1 begin>
>>                         heavy code
>>                 <region 1 end>
>>                         trivial code
>>         }
>> 
>> but this appears to do
>> ...
>> which is somewhat puzzling.
>
> I notice that a v4 was sent that adds more sub-regions without actually
> responding to this request. (It is worth also pointing out that you
> ignored Junio's request you use the cover letter to explain your reasoning
> for changes between versions.)

> There is a real downside to nesting regions like this. Specifically, we
> frequently limit the depth that we report nested regions to avoid
> overwhelming the logs.
>
> In general, these sub-regions should be avoided when possible and instead
> create regions around important sections, such as the second option Junio
> lists above.