On 06/18/2012 06:13 PM, Michael S. Tsirkin wrote:
On Mon, Jun 18, 2012 at 04:03:23PM +0800, Asias He wrote:
On 06/18/2012 03:46 PM, Rusty Russell wrote:
On Mon, 18 Jun 2012 14:53:10 +0800, Asias He <asias@xxxxxxxxxx> wrote:
This patch introduces bio-based IO path for virtio-blk.
Why make it optional?
request-based IO path is useful for users who do not want to bypass
the IO scheduler in guest kernel, e.g. users using spinning disk.
For users using fast disk device, e.g. SSD device, they can use
bio-based IO path.
OK I guess but then it should be per-device. There could be
a mix of slow and fast disks :)
Yes, per-device might be useful. There are issues which need solving.
- How do we tell the drive which IO path to use
- Device add some flag
- Old qemu/lkvm can not turn this feature on
- Through /sys filesystem attribute
- How do we handle the switch from one path to anther.
So, let's add the per-device feature later.
--
Asias
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