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[PATCH 0/2] block: propagate discard alignment from format drivers to th
From: |
Denis V. Lunev |
Subject: |
[PATCH 0/2] block: propagate discard alignment from format drivers to the guest |
Date: |
Thu, 11 Jun 2020 20:16:06 +0300 |
Nowaday SCSI drivers in guests are able to align UNMAP requests before
sending to the device. Right now QEMU provides an ability to set
this via "discard_granularity" property of the block device which could
be used by management layer.
Though, in particular, from the point of QEMU, there is
pdiscard_granularity on the format driver level, f.e. on QCOW2 or iSCSI.
It would be beneficial to pass this value as a default for this
property.
Technically this should reduce the amount of use less UNMAP requests
from the guest to the host. Basic test confirms this. Fedora 31 guest
during 'fstrim /' on 32 Gb disk has issued 401/415 requests with/without
proper alignment to QEMU.
Changes from v2:
- 172 iotest fixed
Changes from v1:
- fixed typos in description
- added machine type compatibility layer as suggested by Kevin
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
CC: Eduardo Habkost <ehabkost@redhat.com>
CC: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
CC: John Snow <jsnow@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Fam Zheng <fam@euphon.net>
- [PATCH 0/2] block: propagate discard alignment from format drivers to the guest,
Denis V. Lunev <=
- [PATCH 1/2] block: propagate discard alignment from format drivers to the guest, Denis V. Lunev, 2020/06/11
- [PATCH 2/2] iotests: fix 172 test, Denis V. Lunev, 2020/06/11
- pls consider this is [v3] Re: [PATCH 0/2] block: propagate discard alignment from format drivers to the guest, Denis V. Lunev, 2020/06/11
- Re: [PATCH 0/2] block: propagate discard alignment from format drivers to the guest, Eduardo Habkost, 2020/06/19
- Re: [PATCH 0/2] block: propagate discard alignment from format drivers to the guest, Denis V. Lunev, 2020/06/26