From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: perf CPU profiling in Xen guest fail & workaround Date: Wed, 29 Jul 2015 15:21:54 -0700 Message-ID: <874mkm8v0d.fsf@tassilo.jf.intel.com> References: <55B92661.7010309@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from mga02.intel.com ([134.134.136.20]:53694 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751246AbbG2WV5 (ORCPT ); Wed, 29 Jul 2015 18:21:57 -0400 In-Reply-To: <55B92661.7010309@gmail.com> (David Ahern's message of "Wed, 29 Jul 2015 13:15:45 -0600") Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: David Ahern Cc: Brendan Gregg , "linux-perf-use." David Ahern writes: > > It's a known problem with VMs (Solaris based ldoms and apparently xen > guests as examples). The hypervisor tells perf it has a PMU (see dmesg > | grep Performance) but does not really implement it (no NMIs for > example). Actually Xen has a PMU model. I've never tested it, but from a quick source review some time ago it seemed reasonable for Arch Perfmon v1, when disabled. If something doesn't work you should report it to the Xen people BTW sampling works with KVM's PMU model; I'm using that occasionally. -Andi -- ak@linux.intel.com -- Speaking for myself only