From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: Question about partitioning shared cache in Xen Date: Wed, 14 Jan 2015 15:02:07 +0000 Message-ID: <54B692FF0200007800054F30@mail.emea.novell.com> References: <54B65F04.2080200@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YBPSY-0003at-Kb for xen-devel@lists.xenproject.org; Wed, 14 Jan 2015 15:02:14 +0000 In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Meng Xu Cc: Andrew Cooper , "xen-devel@lists.xenproject.org" List-Id: xen-devel@lists.xenproject.org >>> On 14.01.15 at 15:45, wrote: > Yes. I try to use the bits [A16, A12] to isolate different colors in a > shared cache. A 2MB 16-way associate shared cache uses [A16, A6] to > index the cache set. Because page size is 4KB, we have page frame > number's bits [A16, A12] overlapped with the bits used to index a > shared cache's cache set. So we can control those [A16, A12] bits to > control where the page should be placed. (The wiki pages about page > coloring is here: http://en.wikipedia.org/wiki/Cache_coloring) But the majority of allocations done for guests would be as 2M or 1G pages, so picking address bits 12..16 for coloring seems rather undesirable. (And surely no LLC would be large enough any time soon to allow coloring of 1G pages anyway.) Jan