Am 24.02.2014 um 14:01 hat Peter Lieven geschrieben:
On 24.02.2014 11:38, Paolo Bonzini wrote:
Il 24/02/2014 11:26, Peter Lieven ha scritto:
I personally do not need this for QCOW2 but for iSCSI. Here the optimization
is basically saved bandwidth since a zero write becomes a WRITESAME.
It
Am 25.02.2014 14:41, schrieb Kevin Wolf:
Am 24.02.2014 um 14:01 hat Peter Lieven geschrieben:
On 24.02.2014 11:38, Paolo Bonzini wrote:
Il 24/02/2014 11:26, Peter Lieven ha scritto:
I personally do not need this for QCOW2 but for iSCSI. Here the
optimization
is basically saved bandwidth
Am 22.02.2014 um 14:00 hat Peter Lieven geschrieben:
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
i know that there is a lot of potential for discussion, but i would
like to know what the others think.
this
On 24.02.2014 11:11, Kevin Wolf wrote:
Am 22.02.2014 um 14:00 hat Peter Lieven geschrieben:
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
i know that there is a lot of potential for discussion, but i would
like to
Il 24/02/2014 11:26, Peter Lieven ha scritto:
I personally do not need this for QCOW2 but for iSCSI. Here the optimization
is basically saved bandwidth since a zero write becomes a WRITESAME.
It saves bandwidth, but at the potential cost of extra host CPU
utilization. I would be fine with
Il 24/02/2014 02:01, Fam Zheng ha scritto:
I would do this in qcow2:
1. In qcow2_co_writev, allocate cluster regardless of if data is zero or not.
2. If data is zero, set QCOW2_OFLAG_ZERO in L2.
This is (or should be) bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP.
Paolo
On Mon, 02/24 11:39, Paolo Bonzini wrote:
Il 24/02/2014 02:01, Fam Zheng ha scritto:
I would do this in qcow2:
1. In qcow2_co_writev, allocate cluster regardless of if data is zero or
not.
2. If data is zero, set QCOW2_OFLAG_ZERO in L2.
This is (or should be) bdrv_co_write_zeroes
On 24.02.2014 11:38, Paolo Bonzini wrote:
Il 24/02/2014 11:26, Peter Lieven ha scritto:
I personally do not need this for QCOW2 but for iSCSI. Here the optimization
is basically saved bandwidth since a zero write becomes a WRITESAME.
It saves bandwidth, but at the potential cost of extra
Il 24/02/2014 12:33, Fam Zheng ha scritto:
This is (or should be) bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP.
But IIUC bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP doesn't require
cluster allocation if it's allocated yet, which is a bit different.
Yeah, that's why I wrote or should
Am 24.02.2014 um 12:51 hat Paolo Bonzini geschrieben:
Il 24/02/2014 12:33, Fam Zheng ha scritto:
This is (or should be) bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP.
But IIUC bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP doesn't require
cluster allocation if it's allocated yet, which
On Mon, 02/24 12:51, Paolo Bonzini wrote:
Il 24/02/2014 12:33, Fam Zheng ha scritto:
This is (or should be) bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP.
But IIUC bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP doesn't require
cluster allocation if it's allocated yet, which is a bit
Am 24.02.2014 um 13:10 hat Paolo Bonzini geschrieben:
Il 24/02/2014 13:07, Kevin Wolf ha scritto:
Yeah, that's why I wrote or should be. Those are the intended
semantics of bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP: always
allocate a cluster that will read as zeroes (allocating even
Il 24/02/2014 13:07, Kevin Wolf ha scritto:
Yeah, that's why I wrote or should be. Those are the intended
semantics of bdrv_co_write_zeroes without BDRV_REQ_MAY_UNMAP: always
allocate a cluster that will read as zeroes (allocating even if it
does not necessarily write the zeroes).
Which
On 24.02.2014 11:38, Paolo Bonzini wrote:
Il 24/02/2014 11:26, Peter Lieven ha scritto:
I personally do not need this for QCOW2 but for iSCSI. Here the optimization
is basically saved bandwidth since a zero write becomes a WRITESAME.
It saves bandwidth, but at the potential cost of extra
Am 22.02.2014 17:45, schrieb Fam Zheng:
On Sat, 02/22 14:00, Peter Lieven wrote:
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
i know that there is a lot of potential for discussion, but i would
like to know what
On Sun, 02/23 20:10, Peter Lieven wrote:
Am 22.02.2014 17:45, schrieb Fam Zheng:
On Sat, 02/22 14:00, Peter Lieven wrote:
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
i know that there is a lot of potential
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
i know that there is a lot of potential for discussion, but i would
like to know what the others think.
this should significantly speed up file system initialization and
On Sat, 02/22 14:00, Peter Lieven wrote:
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
i know that there is a lot of potential for discussion, but i would
like to know what the others think.
this should
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