On 19/06/20 18:25, Qais Yousef wrote: > On 06/19/20 16:17, Valentin Schneider wrote: > > [...] > >> > But here this is >> > just extra churn. >> > >> > If an imbalance has happend this means either: >> > >> > 1. enqueue/dequeue_task() is imablanced itself >> > 2. uclamp_update_active() calls dec without inc. >> > >> > If 1 happened we have more reasons to be worried about. For 2 the function >> > takes task_rq_lock() and does dec/inc in obvious way. >> > >> >> True. I won't argue over the feasibility of the scenarios we are currently >> aware of, my point was that if they do happen, it's nice to have debug >> helps in the right places as the final breakage can happen much further >> downstream. >> >> FWIW I don't like the diff I suggested at all, but if we can come up with a >> cleverer scheme I think we should do it, as per the above. > > There's the fact as well that this whole thing is to deal with potentially > avoid doing anything that is stricly not necessary in the fast path. > > keep in mind that my patch of introducing the sysctl is not accepted yet > because it introduces such thing, but in that case it's not a debug only > feature. CONFIG_SCHED_DEBUG do get enabled by distros because it exports a lot > of useful info.
Sigh, true, but they really shouldn't. The whole point of having SCHED_WARN_ON() is that it's a no-op on !SCHED_DEBUG kernels, which should be any "production" kernel :(
