From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: Question about Perf's handling of in-use performance counters Date: Fri, 28 Oct 2016 08:40:12 -0700 Message-ID: <20161028154012.GC26852@two.firstfloor.org> References: <87r371k6gj.fsf@tassilo.jf.intel.com> <20161027210012.GN3102@twins.programming.kicks-ass.net> <20161028135325.GB26852@two.firstfloor.org> <20161028140354.GH3142@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from one.firstfloor.org ([193.170.194.197]:55966 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754677AbcJ1PkQ (ORCPT ); Fri, 28 Oct 2016 11:40:16 -0400 Content-Disposition: inline In-Reply-To: <20161028140354.GH3142@twins.programming.kicks-ass.net> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Andi Kleen , Taylor Andrews , "linux-perf-users@vger.kernel.org" > No, it was about the (mis)guide-line having fundamental races and the > belief that the BIOS has no business what so ever using these resources > to begin with. In this case it's not the BIOS, but a hypervisor who allocates the counter. I believe there are valid use cases here. The same issue can also happen when people use user space perfmon tools, like PCM or likwid, and potentially with other non BIOS users. -Andi