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From: Avi Kivity <avi@redhat.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Cam Macdonell <cam@cs.ualberta.ca>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [PATCH] Inter-VM shared memory PCI device
Date: Thu, 11 Mar 2010 15:07:57 +0200	[thread overview]
Message-ID: <4B98EB2D.4010606@redhat.com> (raw)
In-Reply-To: <201003111357.53025.arnd@arndb.de>

On 03/11/2010 02:57 PM, Arnd Bergmann wrote:
> On Thursday 11 March 2010, Avi Kivity wrote:
>    
>>> A totally different option that avoids this whole problem would
>>> be to separate the signalling from the shared memory, making the
>>> PCI shared memory device a trivial device with a single memory BAR,
>>> and using something a higher-level concept like a virtio based
>>> serial line for the actual signalling.
>>>
>>>        
>> That would be much slower.  The current scheme allows for an
>> ioeventfd/irqfd short circuit which allows one guest to interrupt
>> another without involving their qemus at all.
>>      
> Yes, the serial line approach would be much slower, but my point
> was that we can do signaling over "something else", which could
> well be something building on irqfd.
>    

Well, we could, but it seems to make things more complicated?  A card 
with shared memory, and another card with an interrupt interconnect?

-- 
error compiling committee.c: too many arguments to function


WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Cam Macdonell <cam@cs.ualberta.ca>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: [Qemu-devel] Re: [PATCH] Inter-VM shared memory PCI device
Date: Thu, 11 Mar 2010 15:07:57 +0200	[thread overview]
Message-ID: <4B98EB2D.4010606@redhat.com> (raw)
In-Reply-To: <201003111357.53025.arnd@arndb.de>

On 03/11/2010 02:57 PM, Arnd Bergmann wrote:
> On Thursday 11 March 2010, Avi Kivity wrote:
>    
>>> A totally different option that avoids this whole problem would
>>> be to separate the signalling from the shared memory, making the
>>> PCI shared memory device a trivial device with a single memory BAR,
>>> and using something a higher-level concept like a virtio based
>>> serial line for the actual signalling.
>>>
>>>        
>> That would be much slower.  The current scheme allows for an
>> ioeventfd/irqfd short circuit which allows one guest to interrupt
>> another without involving their qemus at all.
>>      
> Yes, the serial line approach would be much slower, but my point
> was that we can do signaling over "something else", which could
> well be something building on irqfd.
>    

Well, we could, but it seems to make things more complicated?  A card 
with shared memory, and another card with an interrupt interconnect?

-- 
error compiling committee.c: too many arguments to function

  reply	other threads:[~2010-03-11 13:08 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-05 23:52 [PATCH] Support adding a file to qemu's ram allocation Cam Macdonell
2010-03-05 23:52 ` [Qemu-devel] " Cam Macdonell
2010-03-05 23:52 ` [PATCH] Inter-VM shared memory PCI device Cam Macdonell
2010-03-05 23:52   ` [Qemu-devel] " Cam Macdonell
2010-03-07 22:53   ` Paul Brook
2010-03-08  1:45     ` Jamie Lokier
2010-03-08  1:45       ` Jamie Lokier
2010-03-08  9:48       ` Alexander Graf
2010-03-08  9:48         ` Alexander Graf
2010-03-08  9:54         ` Jamie Lokier
2010-03-08  9:54           ` Jamie Lokier
2010-03-08 10:57           ` Alexander Graf
2010-03-08 10:57             ` Alexander Graf
2010-03-09 21:41           ` Anthony Liguori
2010-03-09 21:41             ` Anthony Liguori
2010-03-08 13:04       ` Paul Brook
2010-03-08 13:04         ` Paul Brook
2010-03-09 19:00         ` Jamie Lokier
2010-03-09 19:00           ` Jamie Lokier
2010-03-08  9:52     ` Avi Kivity
2010-03-08  9:52       ` Avi Kivity
2010-03-08 13:03       ` Paul Brook
2010-03-08 13:03         ` Paul Brook
2010-03-08 13:16         ` Avi Kivity
2010-03-08 13:16           ` Avi Kivity
2010-03-09 20:11           ` Jamie Lokier
2010-03-09 20:11             ` Jamie Lokier
2010-03-09 21:44           ` Anthony Liguori
2010-03-09 21:44             ` [Qemu-devel] " Anthony Liguori
2010-03-10  9:25             ` Avi Kivity
2010-03-10  9:25               ` [Qemu-devel] " Avi Kivity
2010-03-10 17:13               ` Anthony Liguori
2010-03-10 17:13                 ` Anthony Liguori
2010-03-10 17:30                 ` Avi Kivity
2010-03-10 17:30                   ` Avi Kivity
2010-03-10 17:41                   ` Paul Brook
2010-03-10 17:41                     ` Paul Brook
2010-03-11  6:33                     ` Avi Kivity
2010-03-11  6:33                       ` Avi Kivity
2010-03-11 12:21                       ` Paul Brook
2010-03-11 12:21                         ` Paul Brook
2010-03-09 20:12         ` Jamie Lokier
2010-03-09 20:12           ` Jamie Lokier
2010-03-10  0:03           ` Paul Brook
2010-03-10  0:03             ` Paul Brook
2010-03-10  4:38             ` Cam Macdonell
2010-03-10  4:38               ` [Qemu-devel] " Cam Macdonell
2010-03-10  9:29               ` Avi Kivity
2010-03-10  9:29                 ` [Qemu-devel] " Avi Kivity
2010-03-10 11:13                 ` Paul Brook
2010-03-10 11:13                   ` Paul Brook
2010-03-11  3:10             ` Jamie Lokier
2010-03-11  3:10               ` Jamie Lokier
2010-03-11  4:37               ` Nick Piggin
2010-03-11  4:37                 ` Nick Piggin
2010-03-11 14:38                 ` malc
2010-03-11 14:38                   ` [Qemu-devel] " malc
2010-03-08  9:56   ` Avi Kivity
2010-03-08  9:56     ` [Qemu-devel] " Avi Kivity
2010-03-08 17:57     ` Cam Macdonell
2010-03-08 17:57       ` [Qemu-devel] " Cam Macdonell
2010-03-09 10:29       ` Avi Kivity
2010-03-09 10:29         ` [Qemu-devel] " Avi Kivity
     [not found]         ` <8286e4ee1003090724m1ef0b571g8b705a24e36e1753@mail.gmail.com>
2010-03-09 15:27           ` Cam Macdonell
2010-03-09 15:27             ` [Qemu-devel] " Cam Macdonell
2010-03-09 17:28             ` Avi Kivity
2010-03-09 17:28               ` [Qemu-devel] " Avi Kivity
2010-03-09 17:34               ` Anthony Liguori
2010-03-09 17:34                 ` [Qemu-devel] " Anthony Liguori
2010-03-09 18:34               ` Cam Macdonell
2010-03-09 18:34                 ` [Qemu-devel] " Cam Macdonell
2010-03-10  9:21                 ` Avi Kivity
2010-03-10  9:21                   ` [Qemu-devel] " Avi Kivity
2010-03-10 16:36                   ` Cam Macdonell
2010-03-10 16:36                     ` [Qemu-devel] " Cam Macdonell
2010-03-11  6:49                     ` Avi Kivity
2010-03-11  6:49                       ` [Qemu-devel] " Avi Kivity
2010-03-09 12:49       ` Arnd Bergmann
2010-03-09 12:49         ` [Qemu-devel] " Arnd Bergmann
2010-03-09 13:03         ` Avi Kivity
2010-03-09 13:03           ` [Qemu-devel] " Avi Kivity
2010-03-09 16:44           ` Cam Macdonell
2010-03-09 16:44             ` [Qemu-devel] " Cam Macdonell
2010-03-10 14:04             ` Arnd Bergmann
2010-03-10 14:04               ` [Qemu-devel] " Arnd Bergmann
2010-03-11  6:50               ` Avi Kivity
2010-03-11  6:50                 ` [Qemu-devel] " Avi Kivity
2010-03-11 12:57                 ` Arnd Bergmann
2010-03-11 12:57                   ` [Qemu-devel] " Arnd Bergmann
2010-03-11 13:07                   ` Avi Kivity [this message]
2010-03-11 13:07                     ` Avi Kivity
2010-03-11 14:32                     ` Arnd Bergmann
2010-03-11 14:32                       ` [Qemu-devel] " Arnd Bergmann
2010-03-08  9:53 ` [PATCH] Support adding a file to qemu's ram allocation Avi Kivity
2010-03-08  9:53   ` [Qemu-devel] " Avi Kivity

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