higher precision timings [ Re: why delta only include the execution time of ngx_process_events not ngx_event_process_posted (Zhang Chao)

Peter Booth peter_booth at me.com
Tue Oct 31 17:25:45 UTC 2017


I think that this discussion touches on another question - are millisecond timings 
still sufficient when monitoring web applications? 

I think that in 2017, with the astounding increases in processing power we 
have seen in the last decade, millisecond timings are too imprecise. The cost
of capturing a timestamp in Linux on recent hardware is about 30 nanos, and
the precision of such a timestamp is also around 30 nanos. I think that there 
is a good argument to be made for exposing timestamps at the maximum level
 of precison possible, rather than hiding what could be useful diagnostic data.

Are there any lans within nginx to report higher resolution timings?

Peter


> On Oct 29, 2017, at 9:35 AM, yang chen <shanchuan04 at gmail.com> wrote:
> 
> Thanks for your reply, why calling the ngx_event_expire_timers is unnecessary when ngx_process_events handler returns so quickly that the
> millisecond precision is not enough to display the calling time(less than
> 1ms maybe).
> 
> ngx_process_events handler returns quickly which doesn't mean ngx_event_process_posted return quickly, maybe it excute for 2 ms or more
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