Morten Brørup, Dec 09, 2025 at 13:11: >> My issue is that I would like the total_objs stat but without the >> overhead of rte_rdtsc() being called twice for every node visit. > > I get that. My proposal provides that.
I didn't get that from your previous message: Morten Brørup, Dec 09, 2025 at 12:13: >>> Looking at patch 2/2, I disagree with the approach. >>> >>> RTE_LIBRTE_GRAPH_STATS should control all stats, incl. total_calls and >>> total_objs. >>> Then, if enabled, the total_cycles stats can be controlled by >>> rte_graph_cycle_stats_enable(). >>> >>> Your v1 series introduces unnecessary overhead for applications not caring >>> about total_calls/total_objs stats and thus built without >>> RTE_LIBRTE_GRAPH_STATS. Where do you propose a new flag to determine whether total_calls and total_objs are updated and total_cycles are not? >> And also, I would like to be able to enable/disable these stats *at >> runtime*. > > Why would you enable/disable total_calls/total_objs at runtime? I don't want to disable/enable total_calls/total_objs. I want to disable/enable total_cycles at runtime. >> Having it behind a compile time constant makes it very not flexible. > > Agree, but instrumentation has a performance cost, and should be > possible to disable at compile time. > >> I could have two booleans to control whether total_calls/total_objs are >> updated *and* whether total_cycles are computed. But that seems a bit >> overkill and it would mean two fields to check (two branches) instead >> of >> one per node. >> >> Is it really that bad to update two uint64_t counters? > > The cost is unnecessary. It's instrumentation. In that instance, I consider total_objs not to be "instrumentation" but more like regular counters (e.g. ethdev stats, xstats, etc.). Unless I am mistaken, there is no way to disable statistics for interfaces for example. For example, in grout, we use total_objs in the main loop to determine if we can save power by willingly putting the CPU to sleep for very short periods of time. If total_objs is no longer updated, grout cannot save power. total_cycles however, *is* instrumentation. It is only useful to identify hotspots and debug issues. But it can be interesting to enable it *at runtime* without recompiling.
