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Date: Sat, 24 Jan 2009 20:39:12 +0200
From: Gleb Natapov <gleb@redhat.com>
Message-ID: <20090124183912.GA7900@redhat.com>
References: <4979D80D.307@us.ibm.com> <20090124171928.GA30108@redhat.com>
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Subject: [Qemu-devel] Re: A new direction for vmchannel?
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Eric Van Hensbergen <ericvanhensbergen@us.ibm.com>, Chris Wright <chrisw@redhat.com>, kvm-devel <kvm@vger.kernel.org>, Dor Laor <dlaor@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Avi Kivity <avi@redhat.com>

On Sat, Jan 24, 2009 at 11:52:06AM -0600, Anthony Liguori wrote:
>> For use cases where you are exposing metadata from the host to the guest
>> this would be a very convenient approach indeed. As asked elsewhere in this
>> thread, my main thought would be about how well it suits a application that
>> wants a generic stream based connection between host & guest ? 
>> Efficient integration into a poll(2) based event loop would be key to 
>> that.
>
> You mean for a very large number of files (determining which property  
> has changed?).
>
I think what Daniel means is that for file to have stream semantic it is
not enough to ignore offset on read/write, but poll also should behave
similar to how it behaves with char device fd. With regular files poll
will always report that fd is ready for I/O.

--
			Gleb.