From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH RFC 2/2] kvm: set affinity hint for assigned device msi Date: Mon, 17 Oct 2011 09:09:46 -0200 Message-ID: <20111017110946.GA21384@amt.cnet> References: <7458f62a58ad7d4022eefba4333336ba268e4ef9.1318358229.git.mst@redhat.com> <20111013145450.GA4143@amt.cnet> <20111016131223.GB17978@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: "Michael S. Tsirkin" Return-path: Content-Disposition: inline In-Reply-To: <20111016131223.GB17978@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Sun, Oct 16, 2011 at 03:12:23PM +0200, Michael S. Tsirkin wrote: > On Thu, Oct 13, 2011 at 11:54:50AM -0300, Marcelo Tosatti wrote: > > On Tue, Oct 11, 2011 at 08:38:28PM +0200, Michael S. Tsirkin wrote: > > > To forward an interrupt to a vcpu that runs on > > > a host cpu different from the current one, > > > we need an ipi which likely will cost us as much > > > as delivering the interrupt directly to that cpu would. > > > > > > Set irq affinity hint to point there, irq balancer > > > can then take this into accound and balance > > > interrupts accordingly. > > > > > > Signed-off-by: Michael S. Tsirkin > > > --- > > > virt/kvm/assigned-dev.c | 8 +++++--- > > > virt/kvm/irq_comm.c | 17 ++++++++++++++++- > > > 2 files changed, 21 insertions(+), 4 deletions(-) Or maybe even automatic in-kernel irq affinity disabled by default (to avoid interference with userspace pinning). All of that if it makes sense performance wise, of course.