From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carsten Otte Subject: Re: [PATCH] kvm memslot read-locking with mmu_lock Date: Wed, 23 Jan 2008 09:15:05 +0100 Message-ID: <4796F789.4080708@de.ibm.com> References: <20080121123710.GF6970@v2.random> <4795F3F0.90403@qumranet.com> <20080122143210.GC7331@v2.random> <4795FFF9.8010400@qumranet.com> <20080122145043.GF7331@v2.random> Reply-To: carsteno-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Avi Kivity To: Andrea Arcangeli Return-path: In-Reply-To: <20080122145043.GF7331-lysg2Xt5kKMAvxtiuMwx3w@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 Andrea Arcangeli wrote: > On Tue, Jan 22, 2008 at 04:38:49PM +0200, Avi Kivity wrote: >> Andrea Arcangeli wrote: >>>> This is arch independent code, I'm surprised mmu_lock is visible here? >>>> >>> The mmu_lock is arch independent as far as I can tell. Pretty much >>> like the mm->page_table_lock is also independent. All archs will have >>> some form of shadow pagetables in software or hardware, and mmu_lock >>> is the lock to take to serialize the pagetable updates and it also >>> allows to walk the memslots in readonly mode. >>> >>> >> Well, s390 has everything in hardware, but I suppose they can just ignore >> the lock. > > If they don't take it in their lowlevel it's enough I think. It'll > still be useful to lookup memslots like in every other arch. The lock won't be a performance issue for s390. We don't need to look them up frequently afaics. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/