Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754586AbbFOPsa (ORCPT ); Mon, 15 Jun 2015 11:48:30 -0400 Received: from casper.infradead.org ([85.118.1.10]:41314 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751098AbbFOPsV (ORCPT ); Mon, 15 Jun 2015 11:48:21 -0400 Date: Mon, 15 Jun 2015 17:48:16 +0200 From: Peter Zijlstra To: Vineet Gupta Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, arnd@arndb.de, Alexey Brodkin , arc-linux-dev@synopsys.com, Arnaldo Carvalho de Melo Subject: Re: [PATCH 4/8] ARCv2: perf: Support sampling events using overflow interrupts Message-ID: <20150615154816.GG3644@twins.programming.kicks-ass.net> References: <1433852372-29494-1-git-send-email-vgupta@synopsys.com> <1433852372-29494-5-git-send-email-vgupta@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1433852372-29494-5-git-send-email-vgupta@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: 2782 Lines: 88 On Tue, Jun 09, 2015 at 05:49:28PM +0530, Vineet Gupta wrote: > From: Alexey Brodkin -ENOCHANGELOG > Cc: Peter Zijlstra > Cc: Arnaldo Carvalho de Melo > Signed-off-by: Alexey Brodkin > Signed-off-by: Vineet Gupta > --- > struct arc_pmu { > struct pmu pmu; > + int has_interrupts; we have pmu::flags & PERF_PMU_CAP_NO_INTERRUPT > @@ -186,7 +189,8 @@ static int arc_pmu_event_init(struct perf_event *event) > hwc->last_period = hwc->sample_period; > local64_set(&hwc->period_left, hwc->sample_period); > } else > - return -ENOENT; > + if (!arc_pmu->has_interrupts) > + return -ENOENT; Same as before, first determine if the event is yours, then return a fatal error. > @@ -307,6 +311,17 @@ static void arc_pmu_stop(struct perf_event *event, int flags) > struct hw_perf_event *hwc = &event->hw; > int idx = hwc->idx; > > + /* Disable interrupt for this counter */ > + if (is_sampling_event(event)) { but but but, a sampling event needs the interrupt enabled? > + /* > + * Reset interrupt flag by writing of 1. This is required > + * to make sure pending interrupt was not left. > + */ Would not typically the interrupt latch be a property of the interrupt controller, not the device generating it? That is, how can the device programming affect pending interrupts? > + write_aux_reg(ARC_REG_PCT_INT_ACT, 1 << idx); > + write_aux_reg(ARC_REG_PCT_INT_CTRL, > + read_aux_reg(ARC_REG_PCT_INT_CTRL) & ~(1 << idx)); > + } > + > + if (is_sampling_event(event)) { > + /* Mimic full counter overflow as other arches do */ With this you mean the pretending we have 63bit of overflow counter? > + write_aux_reg(ARC_REG_PCT_INT_CNTL, arc_pmu->max_period & > + 0xffffffff); Would not (u32)arc_pmu->max_period, be clearer? > + write_aux_reg(ARC_REG_PCT_INT_CNTH, > + (arc_pmu->max_period >> 32)); But should you not program: min(period, max_period) instead? If the requested period is shorter than your max period you do not want to program the max. Or are you missing a negative somewhere? That is, program the max_period for !sampling events to deal with overflow folding. > + > + /* Enable interrupt for this counter */ > + write_aux_reg(ARC_REG_PCT_INT_CTRL, > + read_aux_reg(ARC_REG_PCT_INT_CTRL) | (1 << idx)); > + } > + > write_aux_reg(ARC_REG_PCT_CONFIG, 0); > write_aux_reg(ARC_REG_PCT_COUNTL, 0); > write_aux_reg(ARC_REG_PCT_COUNTH, 0); -- 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/