From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srivatsa Vaddagiri Subject: Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support pv-ticketlock Date: Wed, 19 Jan 2011 23:59:41 +0530 Message-ID: <20110119182940.GA7235__34245.9155167036$1295461989$gmane$org@linux.vnet.ibm.com> References: <20110119164432.GA30669@linux.vnet.ibm.com> <20110119171239.GB726@linux.vnet.ibm.com> <1295457672.28776.144.camel@laptop> Reply-To: vatsa@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1295457672.28776.144.camel@laptop> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Peter Zijlstra Cc: Xen-devel , Mathieu Desnoyers , Nick Piggin , kvm@vger.kernel.org, Linux Kernel Mailing List , Jan Beulich , Eric Dumazet , Jeremy Fitzhardinge , suzuki@in.ibm.com, Avi Kivity , "H. Peter Anvin" , =?iso-8859-1?Q?Am=E9rico?= Wang , Linux Virtualization List-Id: virtualization@lists.linuxfoundation.org On Wed, Jan 19, 2011 at 06:21:12PM +0100, Peter Zijlstra wrote: > I didn't really read the patch, and I totally forgot everything from > when I looked at the Xen series, but does the Xen/KVM hypercall > interface for this include the vcpu to await the kick from? No not yet, for reasons you mention below. > My guess is not, since the ticket locks used don't know who the owner > is, which is of course, sad. There are FIFO spinlock implementations > that can do this though.. although I think they all have a bigger memory > footprint. > > The reason for wanting this should be clear I guess, it allows PI. Yeah - that would be good to experiment with. - vatsa