linux-kernel - Re: [PATCH -v3 1/2] ratelimit: Extend to print suppressed messages on release

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Date:	Tue, 05 Jul 2016 13:08:53 -0700
From:	Joe Perches <joe@...ches.com>
To:	Steven Rostedt <rostedt@...dmis.org>,
	Borislav Petkov <bp@...en8.de>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Radim Krčmář <rkrcmar@...hat.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	Cornelia Huck <cornelia.huck@...ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Franck Bui <fbui@...e.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH -v3 1/2] ratelimit: Extend to print suppressed messages
 on release

On Tue, 2016-07-05 at 15:49 -0400, Steven Rostedt wrote:
> On Tue, 5 Jul 2016 21:42:45 +0200 Borislav Petkov <bp@...en8.de> wrote:
> > On Tue, Jul 05, 2016 at 02:57:32PM -0400, Steven Rostedt wrote:
> > > Perhaps we should show both, unless you don't think this will ever be
> > > used by anything other than devkmsg?  
> > I'd say let's do it only when we go down that road and start using it
> > for something else.
> > 
> > Because, for example, the ratelimiting thing is, in fact, generic but it
> > is used primarily to ratelimit printks. Even though it could be used for
> > something else, theoretically...
> > 
> But you know... Build it and they will come.

arch/s390/kvm/kvm-s390.c:       ratelimit_state_init(&kvm->arch.sthyi_limit, 5 * HZ, 500);

As far as I know, _ratelimit is used for non-printk purposes in
arch/s390/kvm/sthyi.c

int handle_sthyi(struct kvm_vcpu *vcpu)
{
	int reg1, reg2, r = 0;
	u64 code, addr, cc = 0;
	struct sthyi_sctns *sctns = NULL;

	/*
	 * STHYI requires extensive locking in the higher hypervisors
	 * and is very computational/memory expensive. Therefore we
	 * ratelimit the executions per VM.
	 */
	if (!__ratelimit(&vcpu->kvm->arch.sthyi_limit)) {
		kvm_s390_retry_instr(vcpu);
		return 0;
	}