Re: [PATCH] KVM: MMU: Inform users of mmio generation wraparound

[Takuya Yoshikawa <takuya.yoshikawa@gmail.com>]

On Thu, 20 Jun 2013 15:14:42 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> Il 20/06/2013 14:54, Gleb Natapov ha scritto:
> >> If they see mysterious peformance problems induced by this wraparound, the only
> >> way to know the cause later is by this kind of information in the syslog.
> >> So even the first wraparound may better be printed out IMO.
> > Think about starting hundreds VMs on a freshly booted host. You will see
> > hundreds of those pretty quickly.
> 
> With the change I made to Xiao's patch (changing -13 to -150) you won't
> see it immediately after startup, but the first wraparound may still
> come very soon with a loop that reads the ROM.  (The second takes 5
> minutes).
> 
> >> I want to let administrators know the cause if possible, any better way?
> >>
> > Not that I can think of. Paolo what about print_once() and ignore first
> > wraparound?
> 
> printk_ratelimited is enough, even without ignoring the first
> wraparound.  It will handle the case of multiple VMs too.

OK, I'm now trying printk_ratelimited() version.
Will send v2 if it works.

	Takuya