Thomas wrote: > On Tue, Jan 17 2023 at 10:18, Boqun Feng wrote: > > On Mon, Jan 16, 2023 at 10:00:52AM -0800, Linus Torvalds wrote: > > > I also recall this giving a fair amount of false positives, are they all fixed? > > > > From the following part in the cover letter, I guess the answer is no? > > ... > > 6. Multiple reports are allowed. > > 7. Deduplication control on multiple reports. > > 8. Withstand false positives thanks to 6. > > ... > > > > seems to me that the logic is since DEPT allows multiple reports so that > > false positives are fitlerable by users? > > I really do not know what's so valuable about multiple reports. They > produce a flood of information which needs to be filtered, while a > single report ensures that the first detected issue is dumped, which > increases the probability that it can be recorded and acted upon. Assuming the following 2 assumptions, you are right. Assumption 1. There will be too many reports with the multi-report support, like all the combination of dependencies between e.g. in-irq and irq-enabled-context. Assumption 2. The detection is matured enough so that it barely happens to fix false onces to see true one which is not a big deal. However, DEPT doesn't generate all the combination of irq things as Lockdep does so we only see a few multi-reports even with the support, and I admit DEPT hasn't matured enough yet because fine classification is required anyway to suppress false alarms. That's why I introduced multi-report support at least for now. IMHO, it'd be still useful even if it's gonna report a few true ones at once w/o false ones some day. > Filtering out false positives is just the wrong approach. Decoding > dependency issues from any tracker is complex enough given the nature of > the problem, so adding the burden of filtering out issues from a stream > of dumps is not helpful at all. It's just a marketing gag. > > > * Instead of introducing a brand new detector/dependency tracker, > > could we first improve the lockdep's dependency tracker? I think > > Byungchul also agrees that DEPT and lockdep should share the > > same dependency tracker and the benefit of improving the > > existing one is that we can always use the self test to catch > > any regression. Thoughts? > > Ack. If the internal implementation of lockdep has shortcomings, then we > can expand and/or replace it instead of having yet another > infrastructure which is not even remotely as mature. Ultimately, yes. We should expand or replace it instead of having another ultimately. Byungchul > > Thanks, > > tglx
