From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v3 6/9] kvm: arm/arm64: Add host pmu to support VM introspection Date: Wed, 18 Jan 2017 13:45:58 +0000 Message-ID: <20170118134558.GF28063@arm.com> References: <20170110113856.7183-1-punit.agrawal@arm.com> <20170110113856.7183-7-punit.agrawal@arm.com> <1a6b8d71-58a5-b29b-3f01-e945deb2baf6@arm.com> <20170118113523.GB3231@leverpostej> <87o9z4msi3.fsf@e105922-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id EC30D4078A for ; Wed, 18 Jan 2017 08:44:06 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PWPuwkPJrFqg for ; Wed, 18 Jan 2017 08:44:05 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id BA143406B8 for ; Wed, 18 Jan 2017 08:44:05 -0500 (EST) Content-Disposition: inline In-Reply-To: <87o9z4msi3.fsf@e105922-lin.cambridge.arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Punit Agrawal Cc: kvm@vger.kernel.org, Marc Zyngier , linux-kernel@vger.kernel.org, Steven Rostedt , Peter Zijlstra , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu On Wed, Jan 18, 2017 at 01:01:40PM +0000, Punit Agrawal wrote: > Mark Rutland writes: > > > On Wed, Jan 18, 2017 at 11:21:21AM +0000, Marc Zyngier wrote: > >> On 10/01/17 11:38, Punit Agrawal wrote: > >> > +#define VM_MASK GENMASK_ULL(31, 0) > >> > +#define EVENT_MASK GENMASK_ULL(32, 39) > >> > +#define EVENT_SHIFT (32) > >> > + > >> > +#define to_pid(cfg) ((cfg) & VM_MASK) > >> > +#define to_event(cfg) (((cfg) & EVENT_MASK) >> EVENT_SHIFT) > >> > + > >> > +PMU_FORMAT_ATTR(vm, "config:0-31"); > >> > +PMU_FORMAT_ATTR(event, "config:32-39"); > >> > >> I'm a bit confused by these. Can't you get the PID of the VM you're > >> tracing directly from perf, without having to encode things? > > With perf attached to a PID, the event gets scheduled out when the task > is context switched. As the PID of the controlling process was used, > none of the vCPU events were counted. So it sounds like userspace needs to deal with this by attaching to the PIDs of the vCPUs. Given that perf kvm seems to have knowledge of vCPUs, it would be nice to know why that logic isn't reusable here. Take a look in tools/perf/builtin-kvm.c and if it's not up to the job, then perhaps it can be improved. Will From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 18 Jan 2017 13:45:58 +0000 Subject: [PATCH v3 6/9] kvm: arm/arm64: Add host pmu to support VM introspection In-Reply-To: <87o9z4msi3.fsf@e105922-lin.cambridge.arm.com> References: <20170110113856.7183-1-punit.agrawal@arm.com> <20170110113856.7183-7-punit.agrawal@arm.com> <1a6b8d71-58a5-b29b-3f01-e945deb2baf6@arm.com> <20170118113523.GB3231@leverpostej> <87o9z4msi3.fsf@e105922-lin.cambridge.arm.com> Message-ID: <20170118134558.GF28063@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jan 18, 2017 at 01:01:40PM +0000, Punit Agrawal wrote: > Mark Rutland writes: > > > On Wed, Jan 18, 2017 at 11:21:21AM +0000, Marc Zyngier wrote: > >> On 10/01/17 11:38, Punit Agrawal wrote: > >> > +#define VM_MASK GENMASK_ULL(31, 0) > >> > +#define EVENT_MASK GENMASK_ULL(32, 39) > >> > +#define EVENT_SHIFT (32) > >> > + > >> > +#define to_pid(cfg) ((cfg) & VM_MASK) > >> > +#define to_event(cfg) (((cfg) & EVENT_MASK) >> EVENT_SHIFT) > >> > + > >> > +PMU_FORMAT_ATTR(vm, "config:0-31"); > >> > +PMU_FORMAT_ATTR(event, "config:32-39"); > >> > >> I'm a bit confused by these. Can't you get the PID of the VM you're > >> tracing directly from perf, without having to encode things? > > With perf attached to a PID, the event gets scheduled out when the task > is context switched. As the PID of the controlling process was used, > none of the vCPU events were counted. So it sounds like userspace needs to deal with this by attaching to the PIDs of the vCPUs. Given that perf kvm seems to have knowledge of vCPUs, it would be nice to know why that logic isn't reusable here. Take a look in tools/perf/builtin-kvm.c and if it's not up to the job, then perhaps it can be improved. Will From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752360AbdARNsH (ORCPT ); Wed, 18 Jan 2017 08:48:07 -0500 Received: from foss.arm.com ([217.140.101.70]:53616 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691AbdARNsG (ORCPT ); Wed, 18 Jan 2017 08:48:06 -0500 Date: Wed, 18 Jan 2017 13:45:58 +0000 From: Will Deacon To: Punit Agrawal Cc: Mark Rutland , Marc Zyngier , kvm@vger.kernel.org, Peter Zijlstra , linux-kernel@vger.kernel.org, Steven Rostedt , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH v3 6/9] kvm: arm/arm64: Add host pmu to support VM introspection Message-ID: <20170118134558.GF28063@arm.com> References: <20170110113856.7183-1-punit.agrawal@arm.com> <20170110113856.7183-7-punit.agrawal@arm.com> <1a6b8d71-58a5-b29b-3f01-e945deb2baf6@arm.com> <20170118113523.GB3231@leverpostej> <87o9z4msi3.fsf@e105922-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87o9z4msi3.fsf@e105922-lin.cambridge.arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 18, 2017 at 01:01:40PM +0000, Punit Agrawal wrote: > Mark Rutland writes: > > > On Wed, Jan 18, 2017 at 11:21:21AM +0000, Marc Zyngier wrote: > >> On 10/01/17 11:38, Punit Agrawal wrote: > >> > +#define VM_MASK GENMASK_ULL(31, 0) > >> > +#define EVENT_MASK GENMASK_ULL(32, 39) > >> > +#define EVENT_SHIFT (32) > >> > + > >> > +#define to_pid(cfg) ((cfg) & VM_MASK) > >> > +#define to_event(cfg) (((cfg) & EVENT_MASK) >> EVENT_SHIFT) > >> > + > >> > +PMU_FORMAT_ATTR(vm, "config:0-31"); > >> > +PMU_FORMAT_ATTR(event, "config:32-39"); > >> > >> I'm a bit confused by these. Can't you get the PID of the VM you're > >> tracing directly from perf, without having to encode things? > > With perf attached to a PID, the event gets scheduled out when the task > is context switched. As the PID of the controlling process was used, > none of the vCPU events were counted. So it sounds like userspace needs to deal with this by attaching to the PIDs of the vCPUs. Given that perf kvm seems to have knowledge of vCPUs, it would be nice to know why that logic isn't reusable here. Take a look in tools/perf/builtin-kvm.c and if it's not up to the job, then perhaps it can be improved. Will