lkml.org 
[lkml]   [2018]   [Aug]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v3 03/14] sched/core: uclamp: add CPU's clamp groups accounting
    From
    Date
    On 08/16/2018 04:21 PM, Quentin Perret wrote:
    > On Thursday 16 Aug 2018 at 15:45:45 (+0200), Dietmar Eggemann wrote:
    >> On 08/16/2018 03:37 PM, Quentin Perret wrote:
    >>>>> IMHO, if this is something which should not happen at all, a BUG_ON() is the
    >>>>> right thing to do here.
    >>>>
    >>>> I don't agree on that. I agree it should not happen but since it's a
    >>>> recoverable error it think we should not panic.
    >>>
    >>> FWIW, if this is a recoverable error, I think Linus will agree with
    >>> Patrick on this one :-)
    >>>
    >>> https://lkml.org/lkml/2016/10/4/1
    >>
    >> Yeah, not really agreeing here that this is a recoverable error.
    >
    > A non-recoverable scenario could be, for example, if you corrupt your
    > stack and there is absolutely _nothing_ you can do to keep the system up
    > and running, because it's just too broken. I don't feel like we're
    > talking about such an extreme case here ...

    Yeah, that's the extreme. But what about this lovely BUG_ON(busiest ==
    env.dst_rq) in fair.c's load_balance()?

    We could recover by just bailing out ;-)

    I guess we know by now that there are different opinions here.

    >
    >> Besides, we
    >> only consider under-run here, what about over-run?

    Important thing is to also detect the over-run, i.e. add the first task
    and the task counter is already > 0.

    >>
    >> Currently this warning doesn't hit and if the code will be changed and it
    >> hits, I still find a BUG_ON more appealing here ...
    >>
    >> So this error scenario can happen over and over again and we always recover
    >> from ? The important thing is that we find the culprit for this behaviour as
    >> fast as possible ...
    >
    > Agreed, we want to debug that ASAP, but WARN should let us do that just
    > fine, I think.

    +1.


    \
     
     \ /
      Last update: 2018-08-16 17:01    [W:2.513 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site