Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755642Ab3EFTCD (ORCPT ); Mon, 6 May 2013 15:02:03 -0400 Received: from merlin.infradead.org ([205.233.59.134]:52873 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755485Ab3EFTCB (ORCPT ); Mon, 6 May 2013 15:02:01 -0400 Date: Mon, 6 May 2013 21:00:24 +0200 From: Peter Zijlstra To: Stephane Eranian Cc: Andi Kleen , "mingo@elte.hu" , LKML Subject: Re: [PATCH] perf, x86: Add workaround for MEM_*_RETIRED errata BV98 Message-ID: <20130506190024.GB17723@dyad.programming.kicks-ass.net> References: <1367261108-9567-1-git-send-email-andi@firstfloor.org> <20130501090718.GA28253@dyad.programming.kicks-ass.net> <20130501111219.GF28253@dyad.programming.kicks-ass.net> <20130501191342.GH17814@two.firstfloor.org> <20130502073252.GG7521@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1294 Lines: 29 On Mon, May 06, 2013 at 07:41:54PM +0200, Stephane Eranian wrote: > Problem is, those events are really important. We need to be able to > measure them. At what cost? If the code we need to make it work is horrendous we need to maintain that too -- possibly quite a lot longer than Intel thinks IVB is relevant. Anyway; since these events are immediately dangerous (they corrupt state) blocking them is the right thing; we can always merge a patch that undoes that once we've figured out a sane way. Currently I'm still waiting for someone to explain (in complete detail) how the corruption manifests. Until that is clear I can't even begin formulating what might be needed to make it work again. One mode that makes sense to me is where CNTx on SMTi corrupts CNTx on SMTj for i != j. However there's also been said that the only case that doesn't corrupt is for SMTj to have all counters disabled -- which contradicts the previous case. The former case we could maybe make work; the latter I can't see how we could possible make work at all. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/