From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com (aserp1040.oracle.com [141.146.126.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3t5DjF0fWyzDrPL for ; Sat, 29 Oct 2016 06:44:16 +1100 (AEDT) Date: Fri, 28 Oct 2016 15:43:25 -0400 From: Konrad Rzeszutek Wilk To: Pan Xinhui Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, linux-s390@vger.kernel.org, xen-devel-request@lists.xenproject.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, kernellwp@gmail.com, jgross@suse.com, David.Laight@ACULAB.COM, rkrcmar@redhat.com, peterz@infradead.org, benh@kernel.crashing.org, bsingharora@gmail.com, will.deacon@arm.com, borntraeger@de.ibm.com, mingo@redhat.com, paulus@samba.org, mpe@ellerman.id.au, pbonzini@redhat.com, paulmck@linux.vnet.ibm.com, boqun.feng@gmail.com Subject: Re: [Xen-devel] [PATCH v6 10/11] x86, xen: support vcpu preempted check Message-ID: <20161028194325.GE2879@char.us.oracle.com> References: <1477642287-24104-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> <1477642287-24104-11-git-send-email-xinhui.pan@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1477642287-24104-11-git-send-email-xinhui.pan@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Oct 28, 2016 at 04:11:26AM -0400, Pan Xinhui wrote: > From: Juergen Gross > > Support the vcpu_is_preempted() functionality under Xen. This will > enhance lock performance on overcommitted hosts (more runnable vcpus > than physical cpus in the system) as doing busy waits for preempted > vcpus will hurt system performance far worse than early yielding. > > A quick test (4 vcpus on 1 physical cpu doing a parallel build job > with "make -j 8") reduced system time by about 5% with this patch. > > Signed-off-by: Juergen Gross > Signed-off-by: Pan Xinhui > --- > arch/x86/xen/spinlock.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c > index 3d6e006..74756bb 100644 > --- a/arch/x86/xen/spinlock.c > +++ b/arch/x86/xen/spinlock.c > @@ -114,7 +114,6 @@ void xen_uninit_lock_cpu(int cpu) > per_cpu(irq_name, cpu) = NULL; > } > > - Spurious change. > /* > * Our init of PV spinlocks is split in two init functions due to us > * using paravirt patching and jump labels patching and having to do > @@ -137,6 +136,8 @@ void __init xen_init_spinlocks(void) > pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); > pv_lock_ops.wait = xen_qlock_wait; > pv_lock_ops.kick = xen_qlock_kick; > + > + pv_lock_ops.vcpu_is_preempted = xen_vcpu_stolen; > } > > /* > -- > 2.4.11 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > https://lists.xen.org/xen-devel