* Bharata B Rao (bharata....@gmail.com) wrote: > On Fri, Nov 6, 2015 at 2:39 PM, Dr. David Alan Gilbert > <dgilb...@redhat.com> wrote: > > * Bharata B Rao (bhar...@linux.vnet.ibm.com) wrote: > >> On Thu, Nov 05, 2015 at 06:10:27PM +0000, Dr. David Alan Gilbert (git) > >> wrote: > >> > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > >> > > >> > This is the 9th cut of my version of postcopy. > >> > > >> > The userfaultfd linux kernel code is now in the upstream kernel > >> > tree, and so 4.3 can be used without modification. > >> > > >> > This qemu series can be found at: > >> > https://github.com/orbitfp7/qemu.git > >> > on the wp3-postcopy-v9 tag > >> > > >> > Testing status: > >> > * Tested heavily on x86 > >> > * Smoke tested on aarch64 (so it does work on different page sizes) > >> > >> Tested minimally on ppc64 with back and forth postcopy migration of > >> unloaded pseries guest within the localhost - works as expected. > >> > >> However I am seeing a failure in one case. I am not sure if this is > >> a user error or a real issue in postcopy migration. If I switch to postcopy > >> migration immediately after starting the migration, I see the migration > >> failing with error: > >> > >> qemu-system-ppc64: qemu_savevm_send_packaged: Unreasonably large packaged > >> state: 25905005 > > > > I put an arbitrary limit of 16MB (see MAX_VM_CMD_PACKAGED_SIZE in > > include/sysemu/sysemu.h) > > on the size of the data accepted into the packaged blob. How big is the > > htab data likely to be? > > HTAB size is a variable and depends on maxmem size. It will be 1/128 > th of maxmem. So for a 32G guest, HTAB will be 256M in size.
OK, that does get a bit big. Two possible fixes; 1 - postcopy htab (I don't know htab to know how hard that is) 2 - do one pass of iterable/non-postcopiable devices before we start the package; I'm just writing a patch to try that; I'll send it to you to let you try once I get it to not-break normal migration. Dave > > Regards, > Bharata. -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK