From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54868) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zug2M-0002YJ-Vw for qemu-devel@nongnu.org; Fri, 06 Nov 2015 07:22:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zug2I-0002PP-Us for qemu-devel@nongnu.org; Fri, 06 Nov 2015 07:22:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37103) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zug2I-0002P9-Pn for qemu-devel@nongnu.org; Fri, 06 Nov 2015 07:22:30 -0500 Date: Fri, 6 Nov 2015 12:22:23 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20151106122222.GF2459@work-vm> References: <1446747083-18205-1-git-send-email-dgilbert@redhat.com> <20151106034846.GC29481@in.ibm.com> <20151106090952.GA2459@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v9 00/56] Postcopy implementation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Bharata B Rao Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, quintela@redhat.com, liang.z.li@intel.com, "qemu-devel@nongnu.org" , luis@cs.umu.se, Bharata B Rao , "amit.shah@redhat.com" , Paolo Bonzini , David Gibson * Bharata B Rao (bharata.rao@gmail.com) wrote: > On Fri, Nov 6, 2015 at 2:39 PM, Dr. David Alan Gilbert > wrote: > > * Bharata B Rao (bharata@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" > >> > > >> > 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 / dgilbert@redhat.com / Manchester, UK