28.08.2019 16:04, Eric Blake wrote:
> On 8/28/19 4:57 AM, Vladimir Sementsov-Ogievskiy wrote:
>
>>> Hence, it is desirable to have a way for clients to specify that a
>>> particular write zero request is being attempted for a fast wipe, and
>>> get an immediate failure if the zero request would ot
On 8/28/19 4:57 AM, Vladimir Sementsov-Ogievskiy wrote:
>> Hence, it is desirable to have a way for clients to specify that a
>> particular write zero request is being attempted for a fast wipe, and
>> get an immediate failure if the zero request would otherwise take the
>> same time as a write.
23.08.2019 17:34, Eric Blake wrote:
> While it may be counterintuitive at first, the introduction of
> NBD_CMD_WRITE_ZEROES and NBD_CMD_BLOCK_STATUS has caused a performance
> regression in qemu [1], when copying a sparse file. When the
> destination file must contain the same contents as the sourc
On Fri, Aug 23, 2019 at 01:58:44PM -0500, Eric Blake wrote:
> On 8/23/19 1:48 PM, Wouter Verhelst wrote:
> > On Fri, Aug 23, 2019 at 09:34:26AM -0500, Eric Blake wrote:
> >> +- bit 4, `NBD_CMD_FLAG_FAST_ZERO`; valid during
> >> + `NBD_CMD_WRITE_ZEROES`. If set, but the server cannot perform the
>
On 8/23/19 1:48 PM, Wouter Verhelst wrote:
> On Fri, Aug 23, 2019 at 09:34:26AM -0500, Eric Blake wrote:
>> +- bit 4, `NBD_CMD_FLAG_FAST_ZERO`; valid during
>> + `NBD_CMD_WRITE_ZEROES`. If set, but the server cannot perform the
>> + write zeroes any faster than it would for an equivalent
>> + `N
On Fri, Aug 23, 2019 at 09:34:26AM -0500, Eric Blake wrote:
> +- bit 4, `NBD_CMD_FLAG_FAST_ZERO`; valid during
> + `NBD_CMD_WRITE_ZEROES`. If set, but the server cannot perform the
> + write zeroes any faster than it would for an equivalent
> + `NBD_CMD_WRITE`,
One way of fulfilling the letter
While it may be counterintuitive at first, the introduction of
NBD_CMD_WRITE_ZEROES and NBD_CMD_BLOCK_STATUS has caused a performance
regression in qemu [1], when copying a sparse file. When the
destination file must contain the same contents as the source, but it
is not known in advance whether th
