Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer

Ingo Molnar
2016-03-08T17:58:12Z

* Ingo Molnar <mingo@kernel.org> wrote:

> Things got a lot more lively after that!
>
> But most of the overhead seems to come from systemd trying to dump core or
> something like that:
>
> 85872 mingo 20 0 34712 3016 2656 S 4.6 0.0 0:00.14 systemd-coredum
> 85440 mingo 20 0 34712 3028 2664 S 4.2 0.0 0:00.13 systemd-coredum
> 85751 mingo 20 0 34712 3076 2716 S 4.2 0.0 0:00.13 systemd-coredum
> 85840 mingo 20 0 34712 2988 2624 S 4.2 0.0 0:00.13 systemd-coredum
> 85861 mingo 20 0 34712 3080 2720 S 4.2 0.0 0:00.13 systemd-coredum
> 85954 mingo 20 0 34712 3028 2664 S 4.2 0.0 0:00.13 systemd-coredum
>
> and I have:
>
> fomalhaut:~/go/src/github.com/google/syzkaller> ulimit -c
> 0
>
> weird ... Has any of you seen such behavior?

So the workaround for that is to disable systemd trying to log every core dump to
the system journal (!), via:

echo > /proc/sys/kernel/core_pattern

Thanks,

Ingo