From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] x86: use 'dom0_mem' to limit the number of pages for dom0 Date: Tue, 23 Aug 2011 10:26:15 +0100 Message-ID: References: <4E5388A30200007800052B77@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4E5388A30200007800052B77@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich , David Vrabel Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 23/08/2011 10:01, "Jan Beulich" wrote: >> diff -r 8d6edc3d26d2 -r 1ec6c392d40f xen/arch/x86/domain_build.c >> --- a/xen/arch/x86/domain_build.c Sat Aug 13 10:14:58 2011 +0100 >> +++ b/xen/arch/x86/domain_build.c Mon Aug 15 11:42:37 2011 +0100 >> @@ -254,6 +254,8 @@ static unsigned long __init compute_dom0 >> } >> #endif >> >> + d->max_pages = min(max_pages, avail); > > Only having noticed this hypervisor side change in the patch set as it > now got applied to -unstable already, I have to object to this: It is > not memory hotplug compatible (i.e. Dom0, at least with a non-pvops > kernel, could have got ballooned up past the original limit once memory > got added to the system, whereas now you limit it to what was there > at boot time). That's true for any domain isn't it? Yet we've got by so far. The max-mem can be adjusted after a domain is created, so it's not incompatible. > If anything, this should be set to just max_pages, not > considering the amount of available memory at all. I suspect that nullifies the aim of the patch... > Besides that the assignment needs to be saturating, as struct domain's > max_pages member is only "unsigned int", whereas the local variables > are all "unsigned long". So in the end this should really be an equivalent > of > > d->max_pages = min(max_pages, UINT_MAX); We should make d->max_pages a ulong or u64. -- Keir