From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: Xen balloon driver improvement (version 1) Date: Thu, 23 Oct 2014 12:00:40 +0100 Message-ID: <1414062040.19198.38.camel@citrix.com> References: <20141022162930.GA8489@zion.uk.xensource.com> <5447EA49.2080008@citrix.com> <20141022182929.GA29147@zion.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141022182929.GA29147@zion.uk.xensource.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: Wei Liu Cc: Stefano Stabellini , Andrew Cooper , xen-devel@lists.xen.org, David Vrabel , Boris Ostrovsky List-Id: xen-devel@lists.xenproject.org On Wed, 2014-10-22 at 19:29 +0100, Wei Liu wrote: > > > For instance, balloon driver can maintain three queues: > > > > > > 1. queue for 2 MB pages > > > 1. queue for 4 KB pages (delegated to core balloon driver) > > > 1. queue for pages used to mapped pages from other domain > > > > What about 1GB pages? > > > > I wouldn't bother with 1GB pages here. Guests which don't have special privileges are limited to 2M contiguous allocations anyway, to stop them from consuming "precious" higher order mappings. I'm not sure that's still worthwhile (e.g. is it valid on ARM or shadow/HAP x86? I'm not sure). > It would require too much work to coalesce 4KB pages to 1GB pages. FWIW in practice You'd probably coalesce 4K pages into 2M and then 2M into 1G.