Re: possible circular locking dependency detected [was: linux-next: Tree for Aug 22]

Sergey Senozhatsky
2017-08-30T06:15:11Z

Hi,

On (08/30/17 14:43), Byungchul Park wrote:
[..]
> > notably slower than earlier 4.13 linux-next. (e.g. scrolling in vim
> > is irritatingly slow)
>
> To Ingo,
>
> I cannot decide if we have to roll back CONFIG_LOCKDEP_CROSSRELEASE
> dependency on CONFIG_PROVE_LOCKING in Kconfig. With them enabled,
> lockdep detection becomes strong but has performance impact. But,
> it's anyway a debug option so IMHO we don't have to take case of the
> performance impact. Please let me know your decision.

well, I expected it :)

I've been running lockdep enabled kernels for years, and was OK with
the performance. but now it's just too much and I'm looking at disabling
lockdep.

a more relevant test -- compilation of a relatively small project

LOCKDEP -CROSSRELEASE -COMPLETIONS LOCKDEP +CROSSRELEASE +COMPLETIONS

real 1m23.722s real 2m9.969s
user 4m11.300s user 4m15.458s
sys 0m49.386s sys 2m3.594s

you don't want to know how much time now it takes to recompile the
kernel ;)

-ss