On Wed, Apr 01, 2020 at 11:16:07PM +0200, Uladzislau Rezki wrote: > On Wed, Apr 01, 2020 at 04:50:12PM -0400, Joel Fernandes wrote: > > On Wed, Apr 01, 2020 at 11:44:15AM -0700, Paul E. McKenney wrote: > > > Hello! > > > > > > What should we be doing to stress-test kfree_rcu(), including its ability > > > to cope with OOM conditions? Yes, rcuperf runs are nice, but they are not > > > currently doing much more than testing base functionality, performance, > > > and scalability. > > > > I already stress kfree_rcu() with rcuperf right now to a point of OOM and > > make sure it does not OOM. The way I do this is set my VM to low memory (like > > 512MB) and then flood kfree_rcu()s. After the shrinker changes, I don't see > > OOM with my current rcuperf settings. > > > > Not saying that my testing is sufficient, just saying this is what I do. It > > would be good to get a real workload to trigger lot of kfree_rcu() activity > > as well especially on low memory systems. Any ideas on that? > > > > One idea could be to trigger memory pressure from unrelated allocations (such > > as userspace memory hogs), and see how it perform with memory-pressure. For > > one, the shrinker should trigger in such situations to force the queue into > > waiting for a GP in such situations instead of batching too much. This would be good! > > We are also missing vmalloc() tests. I remember Vlad had some clever vmalloc > > tests around for his great vmalloc rewrites :). Vlad, any thoughts on getting > > to stress kvfree_rcu()? > > > Actually i updated(localy for my tests) the lib/test_vmalloc.c module with extra > test cases to stress kvfree_rcu() stuff. I think i should add them :) As would this! ;-) Thanx, Paul
