lkml.org 
[lkml]   [2023]   [Aug]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH V4 2/2] rcu: Update jiffies in rcu_cpu_stall_reset()
    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@joelfernandes.org> wrote:
    > >
    > > On Tue, Aug 29, 2023 at 12:08 AM Huacai Chen <chenhuacai@kernel.org> wrote:
    > > >
    > > > Hi, Joel,
    > > >
    > > > On Tue, Aug 29, 2023 at 4:47 AM Joel Fernandes <joel@joelfernandes.org> wrote:
    > > > >
    > > > > Hi Huacai,
    > > > >
    > > > > On Mon, Aug 28, 2023 at 11:13 AM Huacai Chen <chenhuacai@kernel.org> 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@loongson.cn>"

    Thanks, if/when Paul takes it, he could kindly change the Reported-by, or I
    could.

    thanks,

    - Joel

    \
     
     \ /
      Last update: 2023-08-30 21:24    [W:2.627 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site