Re: [Qemu-devel] [PATCH 11/20] mirror: support more than one in-flight AIO operation

[Eric Blake]

On 12/12/2012 06:46 AM, Paolo Bonzini wrote:
> With AIO support in place, we can start copying more than one chunk
> in parallel.  This patch introduces the required infrastructure for
> this: the buffer is split into multiple granularity-sized chunks,
> and there is a free list to access them.
> 
> Because of copy-on-write, a single operation may already require
> multiple chunks to be available on the free list.
> 
> In addition, two different iterations on the HBitmap may want to
> copy the same cluster.  We avoid this by keeping a bitmap of in-flight
> I/O operations, and blocking until the previous iteration completes.
> This should be a pretty rare occurrence, though; as long as there is
> no overlap the next iteration can start before the previous one finishes.
> 
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  block/mirror.c | 109 
> ++++++++++++++++++++++++++++++++++++++++++++++++++-------
>  trace-events   |   4 ++-
>  2 files changed, 100 insertions(+), 13 deletions(-)

Again, my review is weak, but feel free to add:

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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