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

[Peter Lieven <pl@kamp.de>]

Am 28.03.2014 16:53, schrieb Eric Blake:
> 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?

currently there is no qmp query command I would add it to "query-block" if
noone has objections.

I don't think that its needed to change this at runtime.

Setting it at hotplug time is, of course, reasonable.

I will look at this and send a respin.

Thanks for the suggestions,
Peter