From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756325AbbAIMOI (ORCPT ); Fri, 9 Jan 2015 07:14:08 -0500 Received: from mail-we0-f179.google.com ([74.125.82.179]:61218 "EHLO mail-we0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752904AbbAIMOG (ORCPT ); Fri, 9 Jan 2015 07:14:06 -0500 Date: Fri, 9 Jan 2015 12:14:01 +0000 From: Matt Fleming To: Peter Zijlstra 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 v4 10/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs Message-ID: <20150109121401.GB495@console-pimps.org> References: <1415999712-5850-1-git-send-email-matt@console-pimps.org> <1415999712-5850-11-git-send-email-matt@console-pimps.org> <20150106171712.GH3337@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150106171712.GH3337@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 06 Jan, at 06:17:12PM, Peter Zijlstra wrote: > > afaict the again label will try and steal yet another rmid, if rmids > don't decay fast enough, we could end up with all rmids on the limbo > list and none active. Or am I missing something here? You're not missing anything, that's true, we will try and steal more RMIDs. We could perhaps put a limit on how many RMIDs we're willing to steal, but I think it should definitely be > 1 because RMIDs can stabilize out of order. It's worth pointing out that we only steal more RMIDs if the ones on the limbo list have been queued for the "minimum queue time" - it really is a last resort. -- Matt Fleming, Intel Open Source Technology Center