Re: [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On Mon, 2012-06-18 at 14:14 +0300, Dor Laor wrote:
> On 06/18/2012 01:05 PM, Rusty Russell wrote:
> > On Mon, 18 Jun 2012 16:03:23 +0800, Asias He<asias@xxxxxxxxxx>  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.
> >
> > Users using a spinning disk still get IO scheduling in the host though.
> > What benefit is there in doing it in the guest as well?
> 
> The io scheduler waits for requests to merge and thus batch IOs 
> together. It's not important w.r.t spinning disks since the host can do 
> it but it causes much less vmexits which is the key issue for VMs. 

Is the amount of exits caused by virtio-blk significant at all with
EVENT_IDX?

_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization


[KVM Development]     [Libvirt Development]     [Libvirt Users]     [CentOS Virtualization]     [Netdev]     [Ethernet Bridging]     [Linux Wireless]     [Kernel Newbies]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Photo]     [Yosemite]     [Yosemite Forum]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]     [Find Someone Nice]     [Video 4 Linux]     [Linux Resources]
Add to Google Powered by Linux