From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752989AbdARO6a (ORCPT ); Wed, 18 Jan 2017 09:58:30 -0500 Received: from foss.arm.com ([217.140.101.70]:55642 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751779AbdARO62 (ORCPT ); Wed, 18 Jan 2017 09:58:28 -0500 From: Punit Agrawal To: Will Deacon 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 Subject: Re: [PATCH v3 6/9] kvm: arm/arm64: Add host pmu to support VM introspection 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> <20170118134558.GF28063@arm.com> Date: Wed, 18 Jan 2017 14:58:20 +0000 In-Reply-To: <20170118134558.GF28063@arm.com> (Will Deacon's message of "Wed, 18 Jan 2017 13:45:58 +0000") Message-ID: <87bmv4mn3n.fsf@e105922-lin.cambridge.arm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Will Deacon writes: > 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. Thanks for the pointer. I'll have a play with perf kvm to see if it can be leveraged here. > > Will > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm