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DateWed, 5 Jan 2011 14:21:08 +0100
FromIngo Molnar <>
SubjectRe: [PATCH 1/2] panic: ratelimit panic messages

* Don Zickus <dzickus@redhat.com> wrote:

> Sometimes when things go bad, so much spew is coming on the console it is hard
> to figure out what happened. This patch allows you to ratelimit the panic
> messages with the intent that the first panic message will provide the info
> we need to figure out what happened.
>
> Adds new kernel param 'panic_ratelimit=on/<integer in seconds>'
>
> Signed-off-by: Don Zickus <dzickus@redhat.com>
> ---
> Documentation/kernel-parameters.txt | 6 ++++++
> kernel/panic.c | 30 ++++++++++++++++++++++++++++++
> 2 files changed, 36 insertions(+), 0 deletions(-)

Well, but it's not just panics that can occur repeatedly (in fact panics tend to
trigger once), but recursive/repeated oopses.

So if we try to do some sort of 'show first crash, rate-limit afterwards' thing (i'm
still not 100% sure about the wiseness of it) then we should cover all common
occurances of system panics/crashes.

btw., while printk-delay exists and can serve a similar purpose, it's pretty
cumbersome for panic ratelimit: it slows down bootups extremely, and it also slows
down regular, harmless printks.

So having some sort of rate-limit for emitting crash screens may make sense, while
also preserving the oops counter or at least some other notification that we 'lost'
messages.

Ingo


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