Re: [KVM PATCH v10] kvm: add support for irqfd

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Gregory Haskins <ghaskins@novell.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	davidel@xmailserver.org, mtosatti@redhat.com
Subject: Re: [KVM PATCH v10] kvm: add support for irqfd
Date: Sun, 14 Jun 2009 16:30:35 +0300	[thread overview]
Message-ID: <20090614133035.GD10646@redhat.com> (raw)
In-Reply-To: <4A34F9D8.5040306@redhat.com>

On Sun, Jun 14, 2009 at 04:23:36PM +0300, Avi Kivity wrote:
> Michael S. Tsirkin wrote:
>
>  
>
>>> I think Avi asked for this specific feature during review which is the
>>> reason why its there today.  However, I agree that it would probably be
>>> a good idea to put an upper limit on the number of supported aliases
>>> that can be registered.  Will fix.
>>>
>>> Thanks Michael,
>>>
>>> -Greg
>>>
>>>
>>>     
>>
>>
>> Avi, can you elaborate on why do we want to map multiple fds
>> to the same gsi? I think it's better to allow a 1:1 mapping
>> only: if many processes want to trigger interrupts they can
>> all write to the same fd.
>>   
>
> I don't want to assume that the eventfds all come from the same source.
>
> That said, we have a workaround, allocate a new gsi with the same routes  
> and attach the excess eventfds there.

Right. So you are ok with 1:1 irqfd:gsi requirement for now?
This seems nicer than N:1 with an arbitrary N.

-- 
MST