On Wed, Aug 30, 2023 at 12:25:56PM +0800, Huacai Chen wrote: > On Tue, Aug 29, 2023 at 10:46 PM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > On Tue, Aug 29, 2023 at 12:08 AM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote: > > > > > > Hi, Joel, > > > > > > On Tue, Aug 29, 2023 at 4:47 AM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > > > > > Hi Huacai, > > > > > > > > On Mon, Aug 28, 2023 at 11:13 AM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote: > > > > > > > > > [...] > > > > > > > > > > > > > [Huacai] > > > > > > > I also think the original patch should be OK, but I have another > > > > > > > question: what will happen if the current GP ends before > > > > > > > nr_fqs_jiffies_stall reaches zero? > > > > > > > > > > > > Nothing should happen. Stall detection only happens when a GP is in > > > > > > progress. If a new GP starts, it resets nr_fqs_jiffies_stall. > > > > > > > > > > > > Or can you elaborate your concern more? > > > > > OK, I will test your patch these days. Maybe putting > > > > > nr_fqs_jiffies_stall before jiffies_force_qs is better, because I > > > > > think putting an 'int' between two 'long' is wasting space. :) > > > > > > > > That's a good point and I'll look into that. > > > Another point, is it better to replace ULONG_MAX with ULONG_MAX/4 as > > > Paul suggested? > > > > > > > I could do that but I don't feel too strongly about it. I will keep it > > at ULONG_MAX if it's OK with everyone. > > > > > > Meanwhile I pushed the patch out to my 6.4 stable tree for testing on my fleet. > > > > > > > > Ideally, I'd like to change the stall detection test in the rcutorture > > > > to actually fail rcutorture if stalls don't happen in time. But at > > > > least I verified this manually using rcutorture. > > > > > > > > I should also add a documentation patch for stallwarn.rst to document > > > > the understandable sensitivity of RCU stall detection to jiffies > > > > updates (or lack thereof). Or if you have time, I'd appreciate support > > > > on such a patch (not mandatory but I thought it would not hurt to > > > > ask). > > > > > > > > Looking forward to how your testing goes as well! > > > I have tested, it works for KGDB. > > > > Thanks! If you don't mind, I will add your Tested-by tag to the patch > > and send it out soon. My tests also look good! > > You can add my Tested-by, but Reported-by should be "Binbin Zhou > <zhoubinbin@xxxxxxxxxxx>" Thanks, if/when Paul takes it, he could kindly change the Reported-by, or I could. thanks, - Joel
