From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH v3 1/5] xen: introduce two different max_nr_dom0/domU_grant_frames parameters Date: Fri, 10 Oct 2014 10:19:13 +0100 Message-ID: <5437A491.7040601@citrix.com> References: <1412773221-15150-1-git-send-email-stefano.stabellini@eu.citrix.com> <5435550D.9090504@citrix.com> <5435695C.5010309@citrix.com> <5437A867020000780003D84A@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5437A867020000780003D84A@mail.emea.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich , Stefano Stabellini Cc: julien.grall@citrix.com, xen-devel@lists.xensource.com, Ian.Campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On 10/10/14 08:35, Jan Beulich wrote: >>>> On 08.10.14 at 18:42, wrote: >> On 08/10/14 17:01, Stefano Stabellini wrote: >>> On Wed, 8 Oct 2014, David Vrabel wrote: >>>> On 08/10/14 14:00, Stefano Stabellini wrote: >>>>> Remove max_nr_grant_frames, both variable and preprocessor symbol. >>>>> Introduce two global variables max_nr_dom0_grant_frames and >>>>> max_nr_domU_grant_frames, separately configurable via the Xen command line >>>>> option "gnttab_max_nr_frames". >>>> >>>> Why? I can't think of a sensible use case for this and you don't list >>>> one. dom0 doesn't really use grants so its current number grant frames >>>> is usually 1 so it doesn't seem useful to restrict it differently. >>> >>> See the recent discussion with Jan: >>> >>> http://marc.info/?l=xen-devel&m=141260825209210 >> >> I still don't see a use case. Either: >> >> a) dom0 is the driver domain and doesn't need a large number of grants. >> >> or >> >> b) dom0 has a frontend driver, then the driver domain will have to scan >> dom0's grant table thus dom0's grant table must be sized the same as domUs. > > Looks like you missed that max_nr_maptrack_frames(), which I > think you agree is needed in Dom0, also depends on > max_nr_grant_frames. Agreed. > Question then of course is whether the > distinction should be made at that: Allow controlling grant frames > and maptrack frames separately, rather than Dom0 and DomU. This would seem sensible. David