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[Xen-devel] questions about the block backend/frontend driver

  • To: xen-devel@xxxxxxxxxxxxxxxxxxx
  • From: "Yuming fang" <fangyuming.leo@xxxxxxxxx>
  • Date: Mon, 8 Sep 2008 15:05:04 +0800
  • Delivery-date: Mon, 08 Sep 2008 00:05:32 -0700
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Hi, Everyone,
I am trying to understand the code of the block backend/frontend driver. I konw the blkback and blkfront communicate with each other through event channel and buffer ring. But there are some questions I could not understand.
1. When dom0 receive one disk request from domU1 and another disk request from domU2 simultaneously, how these two disk requests are pushed into Linux Kernel I/O Scheduler? How the Xen sort them before pushing them into the Linux Kernel I/O Scheduler?
2. Is there a disk request queue in the Xen to hold these disk requests, so that the Xen could only push the disk requests in the queue into the linux kernel I/O Scheduler?
I would appreciate it very much if anyone could give me some help.
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