[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] [PATCH] PoD: Handle operations properly when domain is dying
> From: George Dunlap [mailto:George.Dunlap@xxxxxxxxxxxxx] > > On Wed, Nov 11, 2009 at 5:58 PM, Dan Magenheimer > <dan.magenheimer@xxxxxxxxxx> wrote: > > Thanks for the detailed explanation. I think > > "Populate on Demand" connotes too much like > > "Copy on Write" and doesn't really describe > > the essence of what is going on: Booting pre-ballooned. > > Thus my confusion. > > Well, "populate on demand" describes exactly what's actually > happening: the p2m table is being populated as it's used, as opposed > to being populated all at once at the beginning. If it was allocating > memory on demand it would have been called "allocate on demand". :-) I understand that from your (developer's) point of view but 99% or more of your customers won't know what a p2m table is or what populating it means and will assume (as I did earlier), since this is a memory-related feature, that "populate" refers to utilizing RAM. It's a cool and valuable feature... I just think it deserves a better name. ;-) > > This is of course less than ideal as it ensures that > > administrators will choose some safe (probably fairly large) > > amount of memory, a significant portion of which will often > > be wasted. But I suppose its better than the (much larger) > > alternative. > > PoD is only meant to keep the domain going until the balloon driver > loads, which should be fairly early in boot. How much is required > changes depending on the OS and the maximum amount of memory; For > Windows XP, 32-bit, with 4GiB maximum (i.e., reported in the e820 > map), 256 KiB is sufficient to start with (if I recall correctly). > For Windows 7, that's a lot higher. I forget the exact number, but > it's 1-2GiB to boot with a 4GiB maximum. Citrix is doing extensive > testing to find out minimums for a large number of configurations, so > that administrators using XenServer can confidently set the value to a > minimum knowing that they're neither wasting memory nor risking a > crash. :-) I guess that makes sense in the Windows world where "distros" can be counted on one or two hands. Dan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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