On 20/03/22(Sun) 05:39, Visa Hankala wrote: > On Sat, Mar 19, 2022 at 12:10:11AM +0100, Alexander Bluhm wrote: > > On Thu, Mar 17, 2022 at 07:25:27AM +0000, Visa Hankala wrote: > > > On Thu, Mar 17, 2022 at 12:42:13AM +0100, Alexander Bluhm wrote: > > > > I would like to use btrace to debug refernce counting. The idea > > > > is to a a tracepoint for every type of refcnt we have. When it > > > > changes, print the actual object, the current counter and the change > > > > value. > > > > > > > Do we want that feature? > > > > > > I am against this in its current form. The code would become more > > > complex, and the trace points can affect timing. There is a risk that > > > the kernel behaves slightly differently when dt has been compiled in. > > > > On our main architectures dt(4) is in GENERIC. I see your timing > > point for uvm structures. > > In my opinion, having dt(4) enabled by default is another reason why > there should be no carte blanche for adding trace points. Each trace > point adds a tiny amount of bloat. Few users will use the tracing > facility. > > Maybe high-rate trace points could be behind a build option...
The whole point of dt(4) is to be able to debug GENERIC kernel. I doubt the cost of an additional if () block matters.
