From mboxrd@z Thu Jan 1 00:00:00 1970 From: Izik Eidus Subject: Re: [PATCH 0/4] Swapping Date: Sat, 13 Oct 2007 22:06:07 +0200 Message-ID: <4711252F.7020505@qumranet.com> References: <47102823.2000600@qumranet.com> <4711210F.40802@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Anthony Liguori Return-path: In-Reply-To: <4711210F.40802-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Anthony Liguori wrote: > Izik Eidus wrote: >> this patchs allow the guest not shadowed memory to be swapped out. >> >> to make it the must effective you should run -kvm-shadow-memory 1 >> (witch will make your machine slow) >> with -kvm-shadow-memory 1, 3giga memory guest can get to be just >> 32mb on physical host! >> >> when not using -kvm-shadow-memory, i saw 4100mb machine getting to as >> low as 168mb on the physical host (not as bad as i thought it would >> be, and surely not as bad as it can be with 41mb of shadow pages :)) >> > > So what exactly does this option do? Is it really worth exposing it > as an option if it slows down guests so much? > > At least, a better name for the option would be nice. > > Regards, > > Anthony Liguori -kvm-shadow-memory was included in kvm from version 46. it control how much pages will be allocated to the shadow cache, (from version 46 the default is 2% of the system (so 4.1giga have about 80 mbs of shadow cache by default)) the problem is that each page that present at the shadow cache ( mmu pages ) cant be swapped out, so as lower as the number of shadow caches you have as more swappable will be useful. (this option (kvm-shadow-memory) was included to make it possible that as less as possible shadow cache memory will be deleated ( beacuse it have big overhead to lose this cache) ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/