From: "Denis V. Lunev" <den@openvz.org>
To: qemu-block@nongnu.org, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <fam@euphon.net>,
Eduardo Habkost <ehabkost@redhat.com>,
Max Reitz <mreitz@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Denis V . Lunev" <den@openvz.org>, John Snow <jsnow@redhat.com>
Subject: [PATCH 0/2] block: propagate discard alignment from format drivers to the guest
Date: Thu, 11 Jun 2020 20:16:06 +0300 [thread overview]
Message-ID: <20200611171608.22052-1-den@openvz.org> (raw)
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>
next reply other threads:[~2020-06-11 17:17 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 17:16 Denis V. Lunev [this message]
2020-06-11 17:16 ` [PATCH 1/2] block: propagate discard alignment from format drivers to the guest Denis V. Lunev
2020-06-11 17:16 ` [PATCH 2/2] iotests: fix 172 test Denis V. Lunev
2020-06-11 17:21 ` pls consider this is [v3] Re: [PATCH 0/2] block: propagate discard alignment from format drivers to the guest Denis V. Lunev
2020-06-19 8:38 ` Denis V. Lunev
2020-06-19 16:20 ` Eduardo Habkost
2020-06-19 16:27 ` Denis V. Lunev
2020-06-26 8:17 ` Denis V. Lunev
2020-07-03 17:36 ` Denis V. Lunev
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