Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758945AbZJPLjY (ORCPT ); Fri, 16 Oct 2009 07:39:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758906AbZJPLjX (ORCPT ); Fri, 16 Oct 2009 07:39:23 -0400 Received: from mail-pz0-f188.google.com ([209.85.222.188]:48483 "EHLO mail-pz0-f188.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758915AbZJPLjV (ORCPT ); Fri, 16 Oct 2009 07:39:21 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=l5OqEuSVTMOGc41aw3SsEhD/4PTGv4fav4JaJIQ2FfkCHLq5XkN1ejX2+3KMVhASfw mGqRHp8BqUbtVa8Cl1U6LfU/MrHsESIwRzKHEq0ipGDyL5jM83FehJjVz4vTKoagZJ7Z 5KbmbIFZoKMj1+i5imIP3nzWhvTvxE3+7+4Uo= From: Wu Zhangjin To: linux-kernel@vger.kernel.org, linux-mips Cc: Ralf Baechle , Thomas Gleixner , Steven Rostedt , Ingo Molnar , Manuel Lauss , Atsushi Nemoto , Wu Zhangjin Subject: [PATCH 2/2] tracing: add high precision version of trace_clock_local() for MIPS Date: Fri, 16 Oct 2009 19:38:25 +0800 Message-Id: <3c1635bdc0297252f619e2e50dc4b56f48446b0e.1255692619.git.wuzhangjin@gmail.com> X-Mailer: git-send-email 1.6.2.1 In-Reply-To: <4205779ae74d7c4144ee6cbf4e3f15f833646356.1255692619.git.wuzhangjin@gmail.com> References: <4205779ae74d7c4144ee6cbf4e3f15f833646356.1255692619.git.wuzhangjin@gmail.com> In-Reply-To: <4205779ae74d7c4144ee6cbf4e3f15f833646356.1255692619.git.wuzhangjin@gmail.com> References: <4205779ae74d7c4144ee6cbf4e3f15f833646356.1255692619.git.wuzhangjin@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3704 Lines: 125 By default, trace_clock_local() call the sched_clock() to get timestamp, in x86, there is a tsc(64bit) based sched_clock(), but in MIPS, the sched_clock() is jiffies based, which can not give enough precision(about 10ms with 1000 HZ). so, we need to implement a higher precision version for MIPS. in MIPS, there is a tsc like clock counter. based on it, we can implement a new trace_clock_local(), but because the clock counter is only 32bit long, we need to handle rollover for it. fortunately, there a high-level abstraction(cyclecounter) of this action implemented in include/linux/clocksource.h, which helps to handle the details behind, we just use it! Signed-off-by: Wu Zhangjin --- arch/mips/kernel/Makefile | 6 +++ arch/mips/kernel/trace_clock.c | 67 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 73 insertions(+), 0 deletions(-) create mode 100644 arch/mips/kernel/trace_clock.c diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile index 8e26e9c..f228868 100644 --- a/arch/mips/kernel/Makefile +++ b/arch/mips/kernel/Makefile @@ -8,6 +8,10 @@ obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \ ptrace.o reset.o setup.o signal.o syscall.o \ time.o topology.o traps.o unaligned.o watch.o +ifdef CONFIG_FUNCTION_TRACER +CFLAGS_REMOVE_trace_clock.o = -pg +endif + obj-$(CONFIG_CEVT_BCM1480) += cevt-bcm1480.o obj-$(CONFIG_CEVT_R4K_LIB) += cevt-r4k.o obj-$(CONFIG_MIPS_MT_SMTC) += cevt-smtc.o @@ -24,6 +28,8 @@ obj-$(CONFIG_SYNC_R4K) += sync-r4k.o obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-$(CONFIG_MODULES) += mips_ksyms.o module.o +obj-$(CONFIG_FTRACE) += trace_clock.o + obj-$(CONFIG_CPU_LOONGSON2) += r4k_fpu.o r4k_switch.o obj-$(CONFIG_CPU_MIPS32) += r4k_fpu.o r4k_switch.o obj-$(CONFIG_CPU_MIPS64) += r4k_fpu.o r4k_switch.o diff --git a/arch/mips/kernel/trace_clock.c b/arch/mips/kernel/trace_clock.c new file mode 100644 index 0000000..435cd56 --- /dev/null +++ b/arch/mips/kernel/trace_clock.c @@ -0,0 +1,67 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive for + * more details. + * + * Copyright (C) 2009 Lemote Inc. & DSLab, Lanzhou University, China + * Author: Wu Zhangjin + */ + +#include +#include + +#include + +/* + * MIPS clock counter based timecounter. + */ + +struct timecounter mips_tc; + +/* + * trace_clock_local(): the simplest and least coherent tracing clock. + * + * Useful for tracing that does not cross to other CPUs nor + * does it go through idle events. + */ +u64 trace_clock_local(void) +{ + unsigned long flags; + u64 clock; + + raw_local_irq_save(flags); + + preempt_disable_notrace(); + + clock = timecounter_read(&mips_tc); + + preempt_enable_no_resched_notrace(); + + raw_local_irq_restore(flags); + + return clock; +} + +static cycle_t mips_cc_read(const struct cyclecounter *cc) +{ + return read_c0_count(); +} + +static struct cyclecounter mips_cc = { + .read = mips_cc_read, + .mask = CLOCKSOURCE_MASK(32), + .shift = 32, +}; + +static int __init mips_timecounter_init(void) +{ + uint64_t mips_freq = mips_hpt_frequency; + + mips_cc.mult = div_sc((unsigned long)mips_freq, NSEC_PER_SEC, 32); + + timecounter_init(&mips_tc, &mips_cc, sched_clock()); + + return 0; +} + +arch_initcall(mips_timecounter_init); -- 1.6.2.1 -- 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/