From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [Qemu-ppc] [RFC PATCH 12/17] PowerPC: booke64: Add DO_KVM kernel hooks Date: Thu, 12 Jul 2012 08:43:04 +1000 Message-ID: <1342046584.18850.40.camel@pasglop> References: <1340627195-11544-1-git-send-email-mihai.caraman@freescale.com> <1340627195-11544-13-git-send-email-mihai.caraman@freescale.com> <1B2CBB56-7180-4A73-8E51-6538A725F710@suse.de> <1341440735.16808.42.camel@pasglop> <300B73AA675FCE4A93EB4FC1D42459FF15CDE6@039-SN2MPN1-013.039d.mgd.msft.net> ,<7305F50A-8E77-4E88-8EB8-4046A7E94DF9@suse.de> <300B73AA675FCE4A93EB4FC1D42459FF15CF83@039-SN2MPN1-013.039d.mgd.msft.net> <1342045680.18850.39.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Caraman Mihai Claudiu-B02008 , "" , KVM list , linuxppc-dev , "qemu-ppc@nongnu.org List" To: Alexander Graf Return-path: Received: from gate.crashing.org ([63.228.1.57]:43253 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751186Ab2GKWnR (ORCPT ); Wed, 11 Jul 2012 18:43:17 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Thu, 2012-07-12 at 00:35 +0200, Alexander Graf wrote: > > On Thu, 2012-07-12 at 00:25 +0200, Alexander Graf wrote: > >> Or just free up another register early on, like here. > > > > If you're going to do that, you want to measure the impact on null > > syscall performance though. > > That should hold true for any change in that code, no? Yes, but adding a gpr save is more invasive (you have to also load it back later on & put it on the stack). Cheers, Ben. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 6F8522C007A for ; Thu, 12 Jul 2012 08:43:11 +1000 (EST) Message-ID: <1342046584.18850.40.camel@pasglop> Subject: Re: [Qemu-ppc] [RFC PATCH 12/17] PowerPC: booke64: Add DO_KVM kernel hooks From: Benjamin Herrenschmidt To: Alexander Graf Date: Thu, 12 Jul 2012 08:43:04 +1000 In-Reply-To: References: <1340627195-11544-1-git-send-email-mihai.caraman@freescale.com> <1340627195-11544-13-git-send-email-mihai.caraman@freescale.com> <1B2CBB56-7180-4A73-8E51-6538A725F710@suse.de> <1341440735.16808.42.camel@pasglop> <300B73AA675FCE4A93EB4FC1D42459FF15CDE6@039-SN2MPN1-013.039d.mgd.msft.net> ,<7305F50A-8E77-4E88-8EB8-4046A7E94DF9@suse.de> <300B73AA675FCE4A93EB4FC1D42459FF15CF83@039-SN2MPN1-013.039d.mgd.msft.net> <1342045680.18850.39.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: "qemu-ppc@nongnu.org List" , Caraman Mihai Claudiu-B02008 , linuxppc-dev , KVM list , "" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2012-07-12 at 00:35 +0200, Alexander Graf wrote: > > On Thu, 2012-07-12 at 00:25 +0200, Alexander Graf wrote: > >> Or just free up another register early on, like here. > > > > If you're going to do that, you want to measure the impact on null > > syscall performance though. > > That should hold true for any change in that code, no? Yes, but adding a gpr save is more invasive (you have to also load it back later on & put it on the stack). Cheers, Ben. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Date: Wed, 11 Jul 2012 22:43:04 +0000 Subject: Re: [Qemu-ppc] [RFC PATCH 12/17] PowerPC: booke64: Add DO_KVM kernel hooks Message-Id: <1342046584.18850.40.camel@pasglop> List-Id: References: <1340627195-11544-1-git-send-email-mihai.caraman@freescale.com> <1340627195-11544-13-git-send-email-mihai.caraman@freescale.com> <1B2CBB56-7180-4A73-8E51-6538A725F710@suse.de> <1341440735.16808.42.camel@pasglop> <300B73AA675FCE4A93EB4FC1D42459FF15CDE6@039-SN2MPN1-013.039d.mgd.msft.net> ,<7305F50A-8E77-4E88-8EB8-4046A7E94DF9@suse.de> <300B73AA675FCE4A93EB4FC1D42459FF15CF83@039-SN2MPN1-013.039d.mgd.msft.net> <1342045680.18850.39.camel@pasglop> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Alexander Graf Cc: Caraman Mihai Claudiu-B02008 , "" , KVM list , linuxppc-dev , "qemu-ppc@nongnu.org List" On Thu, 2012-07-12 at 00:35 +0200, Alexander Graf wrote: > > On Thu, 2012-07-12 at 00:25 +0200, Alexander Graf wrote: > >> Or just free up another register early on, like here. > > > > If you're going to do that, you want to measure the impact on null > > syscall performance though. > > That should hold true for any change in that code, no? Yes, but adding a gpr save is more invasive (you have to also load it back later on & put it on the stack). Cheers, Ben.