From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH 2/2] KVM: PPC: Book3S: Call into C interrupt handlers Date: Fri, 27 Apr 2012 11:37:25 -0500 Message-ID: <4F9ACB45.3040803@freescale.com> References: <1335435543-19690-1-git-send-email-agraf@suse.de> <1335435543-19690-2-git-send-email-agraf@suse.de> <20120427054810.GC1216@drongo> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: Paul Mackerras , kvm list , kvm-ppc , Benjamin Herrenschmidt To: Alexander Graf Return-path: In-Reply-To: Sender: kvm-ppc-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/27/2012 06:23 AM, Alexander Graf wrote: > > On 27.04.2012, at 07:48, Paul Mackerras wrote: > >> Have you measured a performance improvement with this patch? If so >> how big was it? > > Yeah, I tried things on 970 in an mfsprg/mtsprg busy loop. I measured 3 different variants: > > C irq handling: 1004944 exits/sec > asm irq handling: 1001774 exits/sec > asm + hsrr patch: 994719 exits/sec > > So as you can see, that code change does have quite an impact. But > maybe the added complexity isn't worth it? Either way, we should try > and find a solution that works the same way for booke and book3s - I > don't want such an integral part to differ all that much. Is it really added complexity, considering what you can remove from the asm? I went with C handling on bookehv because it seemed simpler (the original internal version had asm handling). -Scott