[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] [Patch 0/7] pvSCSI driver
> Hi James-san, > > On Thu, 21 Feb 2008 14:39:47 +1100 > "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote: > > Just responding to myself, would I be guessing correctly that you > > removed the timeout field to make the request structure smaller? The top > > That is one reason. However, the main reason is as follows. > > The time that guests/host will get is not real world's time on > virtualized environment. The time depends on hypervisor's scheduling. > (Is this assumption right ?) > > > For example, if upper layer of the pvSCSI frontend specified 5 seconds > as timeout, it should be treated as real world's time or within a guest > domain's world time ? > > We didn't have clear answer when we implemented that part. Therefore, > we coded it temporally 5 seconds. > > James-san, how do you think about this issue ? I don't think the exact value of the timeout matters that much. At worst, a 5 second timeout is going to be at least 5 seconds, and probably not much more than that. It's the Linux SCSI subsystem itself that handles the timeout anyway. > By the way, we understand that the 5 seconds is too short to support > tape device. Yes, way too short. For running the HP LT&T (Library and Tape Tools), even 60 seconds is too short for some operations. FYI, I have the HP LT&T working nicely under windows now. All tests succeed, even a firmware update to the tape drive worked. A Read/Write test on a HP LTO2 drive with LTO1 media gives me 13.3MB/s (approx 800MB/minute) for both read and write operations. I assume that a CD or DVD burner would work also, although I don't have one to test. Are you planning on requesting that pvSCSI get merged into the Xen tree once you have the timeout and unload issues sorted out? James _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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