Re: [Qemu-devel] [PATCHv2] block: optimize zero writes with bdrv_write_zeroes

[Eric Blake <eblake@redhat.com>]

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On 03/28/2014 08:46 AM, Peter Lieven wrote:
> this patch tries to optimize zero write requests
> by automatically using bdrv_write_zeroes if it is
> supported by the format.
> 
> This significantly speeds up file system initialization and
> should speed zero write test used to test backend storage
> performance.
> 

> 
>  block.c                   |   39 ++++++++++++++++++++++++++++++++++++++-
>  include/block/block_int.h |   12 ++++++++++++
>  include/qemu-common.h     |    1 +
>  qemu-options.hx           |    6 ++++++
>  util/iov.c                |   21 +++++++++++++++++++++
>  5 files changed, 78 insertions(+), 1 deletion(-)
> 

Is there any QMP query- command that can expose the current setting of
this value?  Is this something worth making changeable during runtime?
Is it something that can be requested per-disk at hotplug time?

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


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