From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38429) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1chDQw-0003Bv-Df for qemu-devel@nongnu.org; Fri, 24 Feb 2017 05:49:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1chDQt-0004R0-CC for qemu-devel@nongnu.org; Fri, 24 Feb 2017 05:49:06 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52694) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1chDQt-0004Pc-6L for qemu-devel@nongnu.org; Fri, 24 Feb 2017 05:49:03 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 473AB19CF24 for ; Fri, 24 Feb 2017 10:49:03 +0000 (UTC) Date: Fri, 24 Feb 2017 10:48:58 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20170224104858.GD2435@work-vm> References: <20170206173306.20603-1-dgilbert@redhat.com> <20170206173306.20603-3-dgilbert@redhat.com> <2d0b399e-3ebe-620c-f845-5f61fc55e170@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2d0b399e-3ebe-620c-f845-5f61fc55e170@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 02/16] postcopy: Transmit and compare individual page sizes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laurent Vivier Cc: qemu-devel@nongnu.org, quintela@redhat.com, aarcange@redhat.com * Laurent Vivier (lvivier@redhat.com) wrote: > On 06/02/2017 18:32, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > When using postcopy with hugepages, we require the source > > and destination page sizes for any RAMBlock to match; note > > that different RAMBlocks in the same VM can have different > > page sizes. > > > > Transmit them as part of the RAM information header and > > fail if there's a difference. > > > > Signed-off-by: Dr. David Alan Gilbert > > --- > > migration/ram.c | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > > > > diff --git a/migration/ram.c b/migration/ram.c > > index b405e4a..5726563 100644 > > --- a/migration/ram.c > > +++ b/migration/ram.c > > @@ -1979,6 +1979,9 @@ static int ram_save_setup(QEMUFile *f, void *opaque) > > qemu_put_byte(f, strlen(block->idstr)); > > qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr)); > > qemu_put_be64(f, block->used_length); > > + if (migrate_postcopy_ram() && block->page_size != qemu_host_page_size) { > > + qemu_put_be64(f, block->page_size); > > + } > > I understand we don't break migration to previous machine type by adding > data in the migration stream because migration is already broken when > block->page_size != qemu_host_page_size. Am I correct? Right, the previous patch - the one with the summary word - should have failed the migration before we get to this point. This patch can detect a more subtle problem - e.g. we still have huge pages used by some of the RAM Blocks, but not all the same ones as the source. Dave > Laurent > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK