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Date: Sun, 1 Jul 2012 22:18:57 +0900
From: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
To: Avi Kivity <avi@redhat.com>
Cc: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>, mtosatti@redhat.com,
        agraf@suse.de, paulus@samba.org, aarcange@redhat.com,
        kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] KVM: MMU: Avoid handling same rmap_pde in
 kvm_handle_hva_range()
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On Sun, 01 Jul 2012 10:41:05 +0300
Avi Kivity <avi@redhat.com> wrote:

> >> > Note: in the new code we could not use trace_kvm_age_page(), so we just
> >> > dropped the point from kvm_handle_hva_range().
> >> > 
> >> 
> >> Can't it be pushed to handler()?
> > 
> > Yes, but it will be changed to print rmap, not hva and gfn.
> > I will do in the next version.
> 
> We should try to avoid changing the tracepoint ABI.  If we pass the
> memslot to handler(), we should be able to reconstruct the gfn and hva.

That's not enough because we only know rmapp in the handler: we also need
level or something.  I agree that passing memslot for keeping the ABI is
good, but how about two more arguments?

BTW, trace_kvm_age_page() is tracing every handler, not just kvm_age_rmapp().
Is this intentional?

If we trace in the caller, in kvm_age_hva(), we know hva, but not gfn.

Thanks,
	Takuya