From: Jan Kiszka Subject: Re: [PATCH] KVM: x86: Convert tsc_write_lock to raw_spinlock Date: Mon, 07 Feb 2011 18:23:49 +0100 Message-ID: <4D502AA5.7040407@siemens.com> References: <4D4BCB97.6000900@siemens.com> <4D4C698A.4010201@redhat.com> <4D4FD8EE.6040009@siemens.com> <4D4FFD97.6010805@redhat.com> <4D5008F0.5060200@siemens.com> <4D500C9F.2080501@redhat.com> <4D50120F.4030809@siemens.com> <4D501547.6040907@redhat.com> <4D501698.1000507@siemens.com> <4D501D43.5060608@redhat.com> <4D5024F3.9090105@siemens.com> <4D5027A1.8000505@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: Zachary Amsden , Marcelo Tosatti , kvm , Linux Kernel Mailing List To: Avi Kivity Return-path: In-Reply-To: <4D5027A1.8000505@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 2011-02-07 18:10, Avi Kivity wrote: > On 02/07/2011 06:59 PM, Jan Kiszka wrote: >>> >>> (well, actually, cpufreq_notifier and kvm_arch_hardware_enable are >>> already non preemptible, and the stats code should just go away?) >> >> The stats code is trivial to convert, so it doesn't matter. > > Removal is easier. Is that stat interface no longer used? > >> But what about mmu_shrink and its list_move_tail? How is this >> synchronized against kvm_destroy_vm - already today? > > kvm_destroy_vm() takes kvm_lock. If a vm is destroyed before > mmu_shrink(), mmu_shrink() will never see it. If we reach mmu_shrink() > before kvm_destroy_vm(), the latter will wait until mmu_shrink() is done. > Ah, I was confused. Would require some more logic if we wanted to make the loop lock-less, though. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux