From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [patch 07/21] Xen-paravirt: remove ctor for pgd cache Date: Fri, 16 Feb 2007 15:33:09 -0800 Message-ID: <45D63F35.3000101@goop.org> References: <20070216022449.739760547@goop.org> <20070216022531.047039320@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Christoph Lameter Cc: Zachary Amsden , xen-devel@lists.xensource.com, virtualization@lists.osdl.org, linux-kernel@vger.kernel.org, Chris Wright , Andi Kleen , Andrew Morton List-Id: virtualization@lists.linuxfoundation.org Christoph Lameter wrote: > On Thu, 15 Feb 2007, Jeremy Fitzhardinge wrote: > > >> Remove the ctor for the pgd cache. There's no point in having the >> cache machinery do this via an indirect call when all pgd are freed in >> the one place anyway. >> > > Great. We finally get rid of this evil ..... > > On second throughts: > > Are you sure that you understand what you are modifying? The ctor is not > called when you allocate an object but when the slab allocates it. Freeing > an object does not make the slab free it. It will hold it for the next > kmalloc. So you may just have reduced performance somewhat by addiung > additional ctor processing and possibly disturbed the preservation of > cache hot pgds. It's true I wrote this patch as a result of accidentally reading slob.c rather than slab.c, which was mostly as a result of hopeful thinking (I knew that there has been discussion about removing all the slab cache stuff, and I assumed that it had already happened). As a result I'm withdrawing this patch for now, but with any luck it will be useful at some point. J