From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42A63ECDE30 for ; Wed, 17 Oct 2018 11:30:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E69532150F for ; Wed, 17 Oct 2018 11:30:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=synopsys.com header.i=@synopsys.com header.b="P8KYkpGM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E69532150F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=synopsys.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727288AbeJQTZp (ORCPT ); Wed, 17 Oct 2018 15:25:45 -0400 Received: from us01smtprelay-2.synopsys.com ([198.182.60.111]:36760 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726990AbeJQTZp (ORCPT ); Wed, 17 Oct 2018 15:25:45 -0400 Received: from mailhost.synopsys.com (mailhost1.synopsys.com [10.12.238.239]) by smtprelay.synopsys.com (Postfix) with ESMTP id 3BC3110C119F; Wed, 17 Oct 2018 04:30:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=synopsys.com; s=mail; t=1539775828; bh=RsXy62R7i6ki4tJxanJXfts6fwobo8gsNK83seZazn8=; h=From:To:Cc:Subject:Date:From; b=P8KYkpGMQwORD0Xk16LbRcg1rz5syecd8txfZoEH+XLiT/Y0FNza671LpLQmuhHiC 1YZ8oBfkkebkpJkwJiiXr/fz0vQbyKNVhuUKs092kLR7ZTYd3BqXf6D8sV3TYA1N5h IHb/CoccgBIN402KcKMs5EFrXBQ2aN1GUzKyrpAsgq3wiHCBtZAH8AsNac/fT4+pq0 Tu0SvjDi8v0zjghzIFQ1k/Jy5+y0cpXu/ssmvYg5XRMGy4lDyUm18F6au52IMVMnc4 RydoRLALQoWARHS1Ts3pI9ila7VwT5Y3bhoUjlCLE9CrFAOLBTDdNIB+CySzw+rh6h 0K5jtxAWJyhUA== Received: from abrodkin-7480l.internal.synopsys.com (unknown [10.121.8.88]) by mailhost.synopsys.com (Postfix) with ESMTP id 617EC582B; Wed, 17 Oct 2018 04:30:26 -0700 (PDT) From: Alexey Brodkin To: linux-kernel@vger.kernel.org Cc: linux-snps-arc@lists.infradead.org, Alexey Brodkin , Daniel Lezcano , Vineet Gupta , Thomas Gleixner Subject: [PATCH v2] clocksource/drivers/arc_timer: Utilize generic sched_clock Date: Wed, 17 Oct 2018 14:30:20 +0300 Message-Id: <20181017113020.7551-1-abrodkin@synopsys.com> X-Mailer: git-send-email 2.17.2 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It turned out we used to use default implementation of sched_clock() from kernel/sched/clock.c which was as precise as 1/HZ, i.e. by default we had 10 msec granularity of time measurement. Now given ARC built-in timers are clocked with the same frequency as CPU cores we may get much higher precision of time tracking. Thus we switch to generic sched_clock which really reads ARC hardware counters. This is especially helpful for measuring short events. That's what we used to have: ------------------------------>8------------------------ $ perf stat /bin/sh -c /root/lmbench-master/bin/arc/hello > /dev/null Performance counter stats for '/bin/sh -c /root/lmbench-master/bin/arc/hello': 10.000000 task-clock (msec) # 2.832 CPUs utilized 1 context-switches # 0.100 K/sec 1 cpu-migrations # 0.100 K/sec 63 page-faults # 0.006 M/sec 3049480 cycles # 0.305 GHz 1091259 instructions # 0.36 insn per cycle 256828 branches # 25.683 M/sec 27026 branch-misses # 10.52% of all branches 0.003530687 seconds time elapsed 0.000000000 seconds user 0.010000000 seconds sys ------------------------------>8------------------------ And now we'll see: ------------------------------>8------------------------ $ perf stat /bin/sh -c /root/lmbench-master/bin/arc/hello > /dev/null Performance counter stats for '/bin/sh -c /root/lmbench-master/bin/arc/hello': 3.004322 task-clock (msec) # 0.865 CPUs utilized 1 context-switches # 0.333 K/sec 1 cpu-migrations # 0.333 K/sec 63 page-faults # 0.021 M/sec 2986734 cycles # 0.994 GHz 1087466 instructions # 0.36 insn per cycle 255209 branches # 84.947 M/sec 26002 branch-misses # 10.19% of all branches 0.003474829 seconds time elapsed 0.003519000 seconds user 0.000000000 seconds sys ------------------------------>8------------------------ Note how much more meaningful is the second output - time spent for execution pretty much matches number of cycles spent (we're running @ 1GHz here). Signed-off-by: Alexey Brodkin Cc: Daniel Lezcano Cc: Vineet Gupta Cc: Thomas Gleixner --- Changes v1 -> v2: * Timer read callbacks marked as "notrace" * ARC Timer1 explicitly described as 32-bit one on sched_clock_register() invocation arch/arc/Kconfig | 1 + drivers/clocksource/Kconfig | 1 + drivers/clocksource/arc_timer.c | 22 ++++++++++++++++++++++ 3 files changed, 24 insertions(+) diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index 5151d81476a1..714f769389a4 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -9,6 +9,7 @@ config ARC def_bool y select ARC_TIMERS + select GENERIC_SCHED_CLOCK select ARCH_HAS_SYNC_DMA_FOR_CPU select ARCH_HAS_SYNC_DMA_FOR_DEVICE select ARCH_HAS_SG_CHAIN diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index dec0dd88ec15..3268dad4effe 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -290,6 +290,7 @@ config CLKSRC_MPS2 config ARC_TIMERS bool "Support for 32-bit TIMERn counters in ARC Cores" if COMPILE_TEST + depends on GENERIC_SCHED_CLOCK select TIMER_OF help These are legacy 32-bit TIMER0 and TIMER1 counters found on all ARC cores diff --git a/drivers/clocksource/arc_timer.c b/drivers/clocksource/arc_timer.c index 20da9b1d7f7d..b28970ca4a7a 100644 --- a/drivers/clocksource/arc_timer.c +++ b/drivers/clocksource/arc_timer.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -88,6 +89,11 @@ static u64 arc_read_gfrc(struct clocksource *cs) return (((u64)h) << 32) | l; } +static notrace u64 arc_gfrc_clock_read(void) +{ + return arc_read_gfrc(NULL); +} + static struct clocksource arc_counter_gfrc = { .name = "ARConnect GFRC", .rating = 400, @@ -111,6 +117,8 @@ static int __init arc_cs_setup_gfrc(struct device_node *node) if (ret) return ret; + sched_clock_register(arc_gfrc_clock_read, 64, arc_timer_freq); + return clocksource_register_hz(&arc_counter_gfrc, arc_timer_freq); } TIMER_OF_DECLARE(arc_gfrc, "snps,archs-timer-gfrc", arc_cs_setup_gfrc); @@ -139,6 +147,11 @@ static u64 arc_read_rtc(struct clocksource *cs) return (((u64)h) << 32) | l; } +static notrace u64 arc_rtc_clock_read(void) +{ + return arc_read_rtc(NULL); +} + static struct clocksource arc_counter_rtc = { .name = "ARCv2 RTC", .rating = 350, @@ -170,6 +183,8 @@ static int __init arc_cs_setup_rtc(struct device_node *node) write_aux_reg(AUX_RTC_CTRL, 1); + sched_clock_register(arc_rtc_clock_read, 64, arc_timer_freq); + return clocksource_register_hz(&arc_counter_rtc, arc_timer_freq); } TIMER_OF_DECLARE(arc_rtc, "snps,archs-timer-rtc", arc_cs_setup_rtc); @@ -185,6 +200,11 @@ static u64 arc_read_timer1(struct clocksource *cs) return (u64) read_aux_reg(ARC_REG_TIMER1_CNT); } +static notrace u64 arc_timer1_clock_read(void) +{ + return arc_read_timer1(NULL); +} + static struct clocksource arc_counter_timer1 = { .name = "ARC Timer1", .rating = 300, @@ -209,6 +229,8 @@ static int __init arc_cs_setup_timer1(struct device_node *node) write_aux_reg(ARC_REG_TIMER1_CNT, 0); write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH); + sched_clock_register(arc_timer1_clock_read, 32, arc_timer_freq); + return clocksource_register_hz(&arc_counter_timer1, arc_timer_freq); } -- 2.17.2