On Mon 2019-10-21 14:42:14, Peter Zijlstra wrote: > On Mon, Aug 19, 2019 at 12:47:30PM +0200, Petr Mladek wrote: > > Some bug report included the same softlockups in flush_tlb_kernel_range() > > in regular intervals. Unfortunately was not clear if there was a progress > > or not. > > > > The situation can be simulated with a simply busy loop: > > > > while (true) > > cpu_relax(); > > > > The softlockup detector produces: > > > > [ 168.277520] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865] > > [ 196.277604] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865] > > [ 236.277522] watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [cat:4865] > > > > One would expect only one softlockup report or several reports with > > an increased duration. > > Let's just say our expectations differ. > > > The result is that each softlockup is reported only once unless > > another process get scheduled: > > > > [ 320.248948] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4916] > > Which would greatly confuse me; as the above would have me think the > situation got resolved (no more lockups reported) even though it is > still very much stuck there. > > IOW, I don't see how this makes anything better. You're removing > information.
The 2nd patch brings back the regular report but with correctly counted time (stuck for XXs). I split it into two patches because I was not sure what would be preferred behavior. I prefer the regular reports as well. Best Regards, Petr
