Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756850AbbHZOct (ORCPT ); Wed, 26 Aug 2015 10:32:49 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:54115 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752102AbbHZOcr (ORCPT ); Wed, 26 Aug 2015 10:32:47 -0400 Date: Wed, 26 Aug 2015 16:32:42 +0200 From: Peter Zijlstra To: Alexey Brodkin Cc: "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Vineet.Gupta1@synopsys.com" , "arc-linux-dev@synopsys.com" , "arnd@arndb.de" , "acme@kernel.org" Subject: Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Message-ID: <20150826143242.GU16853@twins.programming.kicks-ass.net> References: <1440426023-2792-1-git-send-email-abrodkin@synopsys.com> <1440426023-2792-4-git-send-email-abrodkin@synopsys.com> <20150826131225.GD19282@twins.programming.kicks-ass.net> <1440595268.15478.47.camel@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1440595268.15478.47.camel@synopsys.com> 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: 1482 Lines: 40 On Wed, Aug 26, 2015 at 01:21:08PM +0000, Alexey Brodkin wrote: > Hi Peter, > > On Wed, 2015-08-26 at 15:12 +0200, Peter Zijlstra wrote: > > On Mon, Aug 24, 2015 at 05:20:20PM +0300, Alexey Brodkin wrote: > > > @@ -295,6 +317,16 @@ static int arc_pmu_add(struct perf_event *event, int flags) > > > } > > > > > > write_aux_reg(ARC_REG_PCT_INDEX, idx); > > > + > > > + arc_pmu->act_counter[idx] = event; > > > + > > > + if (is_sampling_event(event)) { > > > + /* Mimic full counter overflow as other arches do */ > > > + write_aux_reg(ARC_REG_PCT_INT_CNTL, (u32)arc_pmu->max_period); > > > + write_aux_reg(ARC_REG_PCT_INT_CNTH, > > > + (arc_pmu->max_period >> 32)); > > > + } > > > + > > > > pmu::add should call pmu::start when PERF_EF_START, without that it > > should not start the counter, only schedule it. > > > > (although currently all pmu::add() calls will have EF_START set) > > And that's what we do, don't we? > ----------------------->8----------------------- > if (flags & PERF_EF_START) > arc_pmu_start(event, PERF_EF_RELOAD); > ----------------------->8----------------------- > D'uh indeed! I read that above as enabling it, while what it really does it simply program the interrupt thresholds. -- 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/