On 05/24/2010 10:19 PM, Anthony Liguori wrote:
On 05/24/2010 06:03 AM, Avi Kivity wrote:
On 05/24/2010 11:27 AM, Stefan Hajnoczi wrote:
On Sun, May 23, 2010 at 1:01 PM, Avi Kivity<avi@xxxxxxxxxx> wrote:
On 05/21/2010 12:29 AM, Anthony Liguori wrote:
I'd be more interested in enabling people to build these types of
storage
systems without touching qemu.
Both sheepdog and ceph ultimately transmit I/O over a socket to a
central
daemon, right?
That incurs an extra copy.
Besides a shared memory approach, I wonder if the splice() family of
syscalls could be used to send/receive data through a storage daemon
without the daemon looking at or copying the data?
Excellent idea.
splice() eventually requires a copy. You cannot splice() to linux-aio
so you'd have to splice() to a temporary buffer and then call into
linux-aio. With shared memory, you can avoid ever bringing the data
into memory via O_DIRECT and linux-aio.
If the final destination is a socket, then you end up queuing guest
memory as an skbuff. In theory we could do an aio splice to block
devices but I don't think that's realistic given our experience with aio
changes.
--
error compiling committee.c: too many arguments to function
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