From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cornelia Huck <cornelia.huck@de.ibm.com>
Subject: Re: [PATCH 1/1] KVM: halt_polling: provide a way to qualify wakeups
 during poll
Date: Tue, 3 May 2016 14:56:12 +0200
Message-ID: <20160503145612.58d8da82.cornelia.huck@de.ibm.com>
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Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Radim =?UTF-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
	KVM <kvm@vger.kernel.org>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Jens Freimann <jfrei@linux.vnet.ibm.com>,
	David Hildenbrand <dahi@linux.vnet.ibm.com>,
	Wanpeng Li <kernellwp@gmail.com>,
	David Matlack <dmatlack@google.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
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On Tue,  3 May 2016 14:37:21 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
> index aa69253..92e6fd6 100644
> --- a/include/trace/events/kvm.h
> +++ b/include/trace/events/kvm.h
> @@ -38,22 +38,25 @@ TRACE_EVENT(kvm_userspace_exit,
>  );
> 
>  TRACE_EVENT(kvm_vcpu_wakeup,
> -	    TP_PROTO(__u64 ns, bool waited),
> -	    TP_ARGS(ns, waited),
> +	    TP_PROTO(__u64 ns, bool waited, bool tuned),
> +	    TP_ARGS(ns, waited, tuned),
> 
>  	TP_STRUCT__entry(
>  		__field(	__u64,		ns		)
>  		__field(	bool,		waited		)
> +		__field(	bool,		tuned		)
>  	),
> 
>  	TP_fast_assign(
>  		__entry->ns		= ns;
>  		__entry->waited		= waited;
> +		__entry->tuned		= tuned;
>  	),
> 
> -	TP_printk("%s time %lld ns",
> +	TP_printk("%s time %lld ns, polling %s",
>  		  __entry->waited ? "wait" : "poll",
> -		  __entry->ns)
> +		  __entry->ns,
> +		  __entry->tuned ? "changed" : "unchanged")

I think "changed"/"unchanged" is a bit misleading here, as we do adjust
the intervall if we had an invalid poll... but it's hard to find a
suitable text here.

Just print "poll interval tuned" if we were (a) polling to begin with,
(b) the poll was valid and (c) the interval was actually changed and
print "invalid poll" if that's what happened? Or is that overkill?

>  );
> 
>  #if defined(CONFIG_HAVE_KVM_IRQFD)

Otherwise, looks good to me.