From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Zhang, Xiantao" Subject: RE: x86: use smp_send_reschedule in kvm_vcpu_kick Date: Thu, 12 Mar 2009 10:31:47 +0800 Message-ID: <706158FABBBA044BAD4FE898A02E4BC224451E95@pdsmsx503.ccr.corp.intel.com> References: <20090303001405.GA5889@amt.cnet> <49B4ECB6.8060505@redhat.com> <20090309105855.GA14242@elte.hu> <1236596946.8389.340.camel@laptop> <20090309232350.GA6837@amt.cnet> <49B61E65.4070706@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Cc: Ingo Molnar , "kvm@vger.kernel.org" , Gleb Natapov , Peter Zijlstra To: Avi Kivity , Marcelo Tosatti Return-path: Received: from mga09.intel.com ([134.134.136.24]:33815 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752674AbZCLCds convert rfc822-to-8bit (ORCPT ); Wed, 11 Mar 2009 22:33:48 -0400 In-Reply-To: <49B61E65.4070706@redhat.com> Content-Language: en-US Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity wrote: > Marcelo Tosatti wrote: >> OK, reworked patch: >> - change ia64 in addition to x86 >> - add comment on smp send reschedule handlers about KVM's usage >> >> Untested on IA64. >> >> KVM: use smp_send_reschedule in kvm_vcpu_kick >> >> KVM uses a function call IPI to cause the exit of a guest running on >> a physical cpu. For virtual interrupt notification there is no need >> to wait on IPI receival, or to execute any function. >> >> This is exactly what the reschedule IPI does, without the overhead >> of function IPI. So use it instead of smp_call_function_single in >> kvm_vcpu_kick. >> >> Also change the "guest_mode" variable to a bit in vcpu->requests, and >> use that to collapse multiple IPI's that would be issued between the >> first one and zeroing of guest mode. >> >> This allows kvm_vcpu_kick to called with interrupts disabled. >> > > Looks good. Will wait for Xiantao's test-n-ack before applying. kvm-ia64 is broken due to recent check-ins about irq-bits, and we are trying to fix it. For this patch, ia64 has to export the symbol smp_send_reschedule before applying the patch. Xiantao