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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] maybe revert commit c275a57f5ec3 "xen/balloon: Set balloon's initial state to number of existing RAM pages"
On 03/28/2017 04:08 AM, Jan Beulich wrote: >>>> On 28.03.17 at 03:57, <boris.ostrovsky@xxxxxxxxxx> wrote: >> I think there is indeed a disconnect between target memory (provided by >> the toolstack) and current memory (i.e actual pages available to the guest). >> >> For example >> >> [ 0.000000] BIOS-e820: [mem 0x000000000009e000-0x000000000009ffff] >> reserved >> [ 0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] >> reserved >> >> are missed in target calculation. The hvmloader marks them as RESERVED >> (in build_e820_table()) but target value is not aware of this action. >> >> And then the same problem repeats when kernel removes >> 0x000a0000-0x000fffff chunk. > But this is all in-guest behavior, i.e. nothing an entity outside the > guest (tool stack or hypervisor) should need to be aware of. That > said, there is still room for improvement in the tools I think: > Regions which architecturally aren't RAM (namely the > 0xa0000-0xfffff range) would probably better not be accounted > for as RAM as far as ballooning is concerned. In the hypervisor, > otoh, all memory assigned to the guest (i.e. including such backing > ROMs) needs to be accounted. On the Linux side we should not include in balloon calculations pages reserved by trim_bios_range(), i.e. (BIOS_END-BIOS_BEGIN) + 1. Which leaves hvmloader's special pages (and possibly memory under 0xA0000 which may get reserved). Can we pass this info to guests via xenstore? -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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