From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755148AbbAOPbd (ORCPT ); Thu, 15 Jan 2015 10:31:33 -0500 Received: from mail-we0-f175.google.com ([74.125.82.175]:35867 "EHLO mail-we0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755117AbbAOPba (ORCPT ); Thu, 15 Jan 2015 10:31:30 -0500 Date: Thu, 15 Jan 2015 15:31:27 +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: <20150115153127.GB3479@codeblueprint.co.uk> 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> <20150109121401.GB495@console-pimps.org> <20150109130250.GH29390@twins.programming.kicks-ass.net> <20150109152442.GG495@console-pimps.org> <20150109155835.GJ29390@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150109155835.GJ29390@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 Fri, 09 Jan, at 04:58:35PM, Peter Zijlstra wrote: > On Fri, Jan 09, 2015 at 03:24:42PM +0000, Matt Fleming wrote: > > > > Right, but now we need a "steal limit", so we know when to stop stealing > > active RMIDs. > > > > (cqm_max_rmid + 1) / 4 ? > > > > I guess any limit is better than no limit. > > Yeah, that'll work, when the free+limbo count is 1/4th the total we > should stop pulling more plugs. We actually stop pulling plugs as soon as there's a single RMID available to use as the rotation RMID. When we find one, we don't wait any longer to do any kind of batching (though if we go from zero available RMIDs, to 5 RMIDs in one loop, we'll pickup all 5 RMIDs). -- Matt Fleming, Intel Open Source Technology Center