From: Stefano Garzarella <sgarzare@redhat.com>
To: "Richard W.M. Jones" <rjones@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org,
Stefan Hajnoczi <stefanha@redhat.com>,
qemu-discuss@nongnu.org
Subject: Re: Interesting qemu/virt-manager bug about the "rotational" attribute on virtio-blk disks
Date: Thu, 16 Jul 2020 11:33:44 +0200 [thread overview]
Message-ID: <20200716093344.7molwklwco4sdtvs@steredhat> (raw)
In-Reply-To: <20200716080614.GA18456@redhat.com>
+Cc Michael, Stefan, virtualization@lists.linux-foundation.org
On Thu, Jul 16, 2020 at 09:06:14AM +0100, Richard W.M. Jones wrote:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1857515
>
> A virtio-blk disk which is backed by a raw file on an SSD,
> inside the guest shows rotational = 1.
>
> I assumed that qemu must have a "rotational" property for disks and
> this would be communicated by virtio to the guest, but qemu and virtio
> don't seem to have this. Pretty surprising! Is it called something
> other than "rotational"?
>
I'm not sure if we need to add this property in QEMU, but in Linux
I found these flags (include/linux/blkdev.h) for the block queues:
#define QUEUE_FLAG_NONROT 6 /* non-rotational device (SSD) */
#define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */
xen-blkfront driver is the only one that sets the QUEUE_FLAG_VIRT,
should we do the same in the virtio-blk driver regardless of the backend?
Thanks,
Stefano
next parent reply other threads:[~2020-07-16 9:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200716080614.GA18456@redhat.com>
2020-07-16 9:33 ` Stefano Garzarella [this message]
2020-07-23 10:32 ` Interesting qemu/virt-manager bug about the "rotational" attribute on virtio-blk disks Stefan Hajnoczi
2020-07-23 10:40 ` Richard W.M. Jones
2020-07-23 11:15 ` Stefano Garzarella
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