From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757729AbbFQGeh (ORCPT ); Wed, 17 Jun 2015 02:34:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49003 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754070AbbFQGe3 (ORCPT ); Wed, 17 Jun 2015 02:34:29 -0400 Date: Wed, 17 Jun 2015 08:34:26 +0200 From: "Michael S. Tsirkin" To: Igor Mammedov Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com Subject: Re: [PATCH 3/5] vhost: support upto 509 memory regions Message-ID: <20150617083202-mutt-send-email-mst@redhat.com> References: <1434472419-148742-1-git-send-email-imammedo@redhat.com> <1434472419-148742-4-git-send-email-imammedo@redhat.com> <20150616231201-mutt-send-email-mst@redhat.com> <20150617000056.481e4a96@igors-macbook-pro.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150617000056.481e4a96@igors-macbook-pro.local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 17, 2015 at 12:00:56AM +0200, Igor Mammedov wrote: > On Tue, 16 Jun 2015 23:14:20 +0200 > "Michael S. Tsirkin" wrote: > > > On Tue, Jun 16, 2015 at 06:33:37PM +0200, Igor Mammedov wrote: > > > since commit > > > 1d4e7e3 kvm: x86: increase user memory slots to 509 > > > > > > it became possible to use a bigger amount of memory > > > slots, which is used by memory hotplug for > > > registering hotplugged memory. > > > However QEMU crashes if it's used with more than ~60 > > > pc-dimm devices and vhost-net since host kernel > > > in module vhost-net refuses to accept more than 65 > > > memory regions. > > > > > > Increase VHOST_MEMORY_MAX_NREGIONS from 65 to 509 > > > > It was 64, not 65. > > > > > to match KVM_USER_MEM_SLOTS fixes issue for vhost-net. > > > > > > Signed-off-by: Igor Mammedov > > > > Still thinking about this: can you reorder this to > > be the last patch in the series please? > sure > > > > > Also - 509? > userspace memory slots in terms of KVM, I made it match > KVM's allotment of memory slots for userspace side. Maybe KVM has its reasons for this #. I don't see why we need to match this exactly. > > I think if we are changing this, it'd be nice to > > create a way for userspace to discover the support > > and the # of regions supported. > That was my first idea before extending KVM's memslots > to teach kernel to tell qemu this number so that QEMU > at least would be able to check if new memory slot could > be added but I was redirected to a more simple solution > of just extending vs everdoing things. > Currently QEMU supports upto ~250 memslots so 509 > is about twice high we need it so it should work for near > future Yes but old kernels are still around. Would be nice if you can detect them. > but eventually we might still teach kernel and QEMU > to make things more robust. A new ioctl would be easy to add, I think it's a good idea generally. > > > > > > > --- > > > drivers/vhost/vhost.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > > index 99931a0..6a18c92 100644 > > > --- a/drivers/vhost/vhost.c > > > +++ b/drivers/vhost/vhost.c > > > @@ -30,7 +30,7 @@ > > > #include "vhost.h" > > > > > > enum { > > > - VHOST_MEMORY_MAX_NREGIONS = 64, > > > + VHOST_MEMORY_MAX_NREGIONS = 509, > > > VHOST_MEMORY_F_LOG = 0x1, > > > }; > > > > > > -- > > > 1.8.3.1