From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH 0/6] x86: reduce paravirtualized spinlock overhead Date: Thu, 30 Apr 2015 09:39:54 -0700 Message-ID: <55425ADA.4060105@goop.org> References: <1430391243-7112-1-git-send-email-jgross@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Juergen Gross , linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, xen-devel@lists.xensource.com, konrad.wilk@oracle.com, david.vrabel@citrix.com, boris.ostrovsky@oracle.com, chrisw@sous-sol.org, akataria@vmware.com, rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, gleb@kernel.org, pbonzini@redhat.com, kvm@vger.kernel.org Return-path: In-Reply-To: <1430391243-7112-1-git-send-email-jgross@suse.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org List-Id: kvm.vger.kernel.org On 04/30/2015 03:53 AM, Juergen Gross wrote: > Paravirtualized spinlocks produce some overhead even if the kernel is > running on bare metal. The main reason are the more complex locking > and unlocking functions. Especially unlocking is no longer just one > instruction but so complex that it is no longer inlined. > > This patch series addresses this issue by adding two more pvops > functions to reduce the size of the inlined spinlock functions. When > running on bare metal unlocking is again basically one instruction. Out of curiosity, is there a measurable difference? J