Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752022AbaKGMVA (ORCPT ); Fri, 7 Nov 2014 07:21:00 -0500 Received: from casper.infradead.org ([85.118.1.10]:35199 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751317AbaKGMU6 (ORCPT ); Fri, 7 Nov 2014 07:20:58 -0500 Date: Fri, 7 Nov 2014 13:20:52 +0100 From: Peter Zijlstra To: Matt Fleming Cc: Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Andi Kleen , Thomas Gleixner , linux-kernel@vger.kernel.org, "H. Peter Anvin" , Kanaka Juvva , Matt Fleming Subject: Re: [PATCH v3 10/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs Message-ID: <20141107122052.GD3337@twins.programming.kicks-ass.net> References: <1415276602-10337-1-git-send-email-matt@console-pimps.org> <1415276602-10337-11-git-send-email-matt@console-pimps.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1415276602-10337-11-git-send-email-matt@console-pimps.org> 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 On Thu, Nov 06, 2014 at 12:23:21PM +0000, Matt Fleming wrote: > +/* > + * If we fail to assign a new RMID for intel_cqm_rotation_rmid because > + * cachelines are still tagged with RMIDs in limbo, we progressively > + * increment the threshold until we find an RMID in limbo with <= > + * __intel_cqm_threshold lines tagged. This is designed to mitigate the > + * problem where cachelines tagged with an RMID are not steadily being > + * evicted. > + * > + * On successful rotations we decrease the threshold back towards zero. > + * > + * __intel_cqm_max_threshold provides an upper bound on the threshold, > + * and is measured in bytes because it's exposed to userland. > + */ > +static unsigned int __intel_cqm_threshold; > +static unsigned int __intel_cqm_max_threshold = -1; Should we initialize that to a finite value? Surely results are absolute crap if we do indeed reach that max? -- 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/