From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH RFC V6 0/11] Paravirtualized ticketlocks Date: Sun, 01 Apr 2012 16:18:25 +0300 Message-ID: <4F7855A1.80107@redhat.com> References: <20120321102041.473.61069.sendpatchset@codeblue.in.ibm.com> <4F707C5F.1000905@redhat.com> <4F716E31.3000803@linux.vnet.ibm.com> <4F73568D.7000703@linux.vnet.ibm.com> <4F743247.5080407@redhat.com> <4F74A405.2040609@linux.vnet.ibm.com> <4F7585EE.7060203@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F7585EE.7060203@linux.vnet.ibm.com> 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: Raghavendra K T Cc: KVM , Alan Meadows , Peter Zijlstra , Stefano Stabellini , the arch/x86 maintainers , LKML , Konrad Rzeszutek Wilk , Andi Kleen , Srivatsa Vaddagiri , Jeremy Fitzhardinge , "H. Peter Anvin" , Attilio Rao , Ingo Molnar , Virtualization , Linus Torvalds , Xen Devel , Stephan Diestelhorst List-Id: virtualization@lists.linuxfoundation.org On 03/30/2012 01:07 PM, Raghavendra K T wrote: > On 03/29/2012 11:33 PM, Raghavendra K T wrote: >> On 03/29/2012 03:28 PM, Avi Kivity wrote: >>> On 03/28/2012 08:21 PM, Raghavendra K T wrote: > >> I really like below ideas. Thanks for that!. >> >>> - from the PLE handler, don't wake up a vcpu that is sleeping >>> because it >>> is waiting for a kick >> >> How about, adding another pass in the beginning of kvm_vcpu_on_spin() >> to check if any vcpu is already kicked. This would almost result in >> yield_to(kicked_vcpu). IMO this is also worth trying. >> >> will try above ideas soon. >> > > I have patch something like below in mind to try: > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index d3b98b1..5127668 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1608,15 +1608,18 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) > * else and called schedule in __vcpu_run. Hopefully that > * VCPU is holding the lock that we need and will release it. > * We approximate round-robin by starting at the last boosted VCPU. > + * Priority is given to vcpu that are unhalted. > */ > - for (pass = 0; pass < 2 && !yielded; pass++) { > + for (pass = 0; pass < 3 && !yielded; pass++) { > kvm_for_each_vcpu(i, vcpu, kvm) { > struct task_struct *task = NULL; > struct pid *pid; > - if (!pass && i < last_boosted_vcpu) { > + if (!pass && !vcpu->pv_unhalted) > + continue; > + else if (pass == 1 && i < last_boosted_vcpu) { > i = last_boosted_vcpu; > continue; > - } else if (pass && i > last_boosted_vcpu) > + } else if (pass == 2 && i > last_boosted_vcpu) > break; > if (vcpu == me) > continue; > Actually I think this is unneeded. The loops tries to find vcpus that are runnable but not running (vcpu_active(vcpu->wq)), and halted vcpus don't match this condition. -- error compiling committee.c: too many arguments to function