Apologies for the confusion; I had the right commit ID but pasted the wrong description. Now fixed, I think!
** Description changed: Commit 633d6f17cd91ad5bf2370265946f716e42d388c6 (aka 38d30afb12140c0e3a446fe779dc9cd29548f313 in vivid) in Xen domU causes high resource requirements in the underlying target dom0 (migrating a 64-bit domU involves a 1GB malloc in dom0, as well as a lot of unnecessary work). In my specific case, that 1GB malloc fails as my dom0s aren't big enough, causing all migrations to fail with the migrating VM suspended. - This is fixed in https://marc.info/?l=git-commits-head&m=142800846201785&w=2 : - "x86/xen: prepare p2m list for memory hotplug": + This is fixed in + http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=98dd166ea3a3c3b57919e20d9b0d1237fcd0349d + : """ - Commit 054954eb051f35e74b75a566a96fe756015352c8 ("xen: switch to linear - virtual mapped sparse p2m list") introduced a regression regarding to - memory hotplug for a pv-domain: as the virtual space for the p2m list - is allocated for the to be expected memory size of the domain only, - hotplugged memory above that size will not be usable by the domain. + x86/xen/p2m: hint at the last populated P2M entry" - Correct this by using a configurable size for the p2m list in case of - memory hotplug enabled (default supported memory size is 512 GB for - 64 bit domains and 4 GB for 32 bit domains). + With commit 633d6f17cd91ad5bf2370265946f716e42d388c6 (x86/xen: prepare + p2m list for memory hotplug) the P2M may be sized to accomdate a much + larger amount of memory than the domain currently has. - Signed-off-by: Juergen Gross <[email protected]> - Cc: <[email protected]> # 3.19+ - Reviewed-by: Daniel Kiper <[email protected]> + When saving a domain, the toolstack must scan all the P2M looking for + populated pages. This results in a performance regression due to the + unnecessary scanning. + + Instead of reporting (via shared_info) the maximum possible size of + the P2M, hint at the last PFN which might be populated. This hint is + increased as new leaves are added to the P2M (in the expectation that + they will be used for populated entries). + Signed-off-by: David Vrabel <[email protected]> + Cc: <[email protected]> # 4.0+ """ -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1542941 Title: Regression: problems migrating recent wily/vivid Xen VMs due to memory hotplug fix To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1542941/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
