From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46634) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1briuO-0000x7-97 for qemu-devel@nongnu.org; Wed, 05 Oct 2016 05:54:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1briuK-0004GQ-3t for qemu-devel@nongnu.org; Wed, 05 Oct 2016 05:54:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34590) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1briuJ-0004GG-UA for qemu-devel@nongnu.org; Wed, 05 Oct 2016 05:54:36 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (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 6084E6365E for ; Wed, 5 Oct 2016 09:54:35 +0000 (UTC) Date: Wed, 5 Oct 2016 10:54:31 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20161005095431.GC2036@work-vm> References: <1475176178-4873-1-git-send-email-dgilbert@redhat.com> <1475176178-4873-3-git-send-email-dgilbert@redhat.com> <20160930080944.GB17928@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160930080944.GB17928@redhat.com> Subject: Re: [Qemu-devel] [PATCH 2/2] migration/postcopy: Explicitly disallow huge pages List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, quintela@redhat.com, amit.shah@redhat.com * Daniel P. Berrange (berrange@redhat.com) wrote: > On Thu, Sep 29, 2016 at 08:09:38PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > At the moment postcopy will fail as soon as qemu tries to register > > userfault on the RAMBlock pages that are backed by hugepages. > > However, the kernel is going to get userfault support for hugepage > > at some point, and we've not got the rest of the QEMU code to support > > it yet, so fail neatly with an error like: > > > > Postcopy doesn't support hugetlbfs yet (/objects/mem1) > > > > Signed-off-by: Dr. David Alan Gilbert > > --- > > migration/postcopy-ram.c | 23 +++++++++++++++++++++++ > > 1 file changed, 23 insertions(+) > > > > diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c > > index 9b04778..9723593 100644 > > --- a/migration/postcopy-ram.c > > +++ b/migration/postcopy-ram.c > > @@ -85,6 +85,23 @@ static bool ufd_version_check(int ufd) > > } > > > > /* > > + * Check for things that postcopy won't support; returns 0 if the block > > + * is fine. > > + */ > > +static int check_range(const char *block_name, void *host_addr, > > + ram_addr_t offset, ram_addr_t length, void *opaque) > > +{ > > + RAMBlock *rb = qemu_ram_block_by_name(block_name); > > + > > + if (qemu_ram_pagesize(rb) > getpagesize()) { > > + error_report("Postcopy doesn't support hugetlbfs yet (%s)", block_name); > > A small nitpick - I'd suggest s/hugetlbfs/large page sizes/ as this error > will ultimately bubble up to users, and 'large page sizes' is the conceptual > feature Interesting, I'd never heard it called 'large' before. Everytime I just say 'huge page' to someone I then have to explain it's fine on transparent huge page. Dave > > > Regards, > Daniel > -- > |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| > |: http://libvirt.org -o- http://virt-manager.org :| > |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :| -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK