From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764201AbZAPE5S (ORCPT ); Thu, 15 Jan 2009 23:57:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757307AbZAPEyZ (ORCPT ); Thu, 15 Jan 2009 23:54:25 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:45871 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756331AbZAPEyU (ORCPT ); Thu, 15 Jan 2009 23:54:20 -0500 Message-Id: <20090116045418.683915469@goodmis.org> References: <20090116045342.748642160@goodmis.org> User-Agent: quilt/0.46-1 Date: Thu, 15 Jan 2009 23:53:48 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker , Steven Rostedt Subject: [PATCH 6/6] trace: set max latency variable to zero on default Content-Disposition: inline; filename=0006-trace-set-max-latency-variable-to-zero-on-default.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt Impact: trace max latencies on start of latency tracing This patch sets the max latency to zero whenever one of the irq variant tracers or the wakeup tracer is set to current tracer. Most developers expect to see output when starting up a latency tracer. But since the max_latency is already set to max, and it takes a latency greater than max_latency to be recorded, there is no trace. This is not the expected behavior and has even confused myself. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 2 +- kernel/trace/trace_irqsoff.c | 1 + kernel/trace/trace_sched_wakeup.c | 1 + 3 files changed, 3 insertions(+), 1 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7de6a94..220c264 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -41,7 +41,7 @@ #define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE) -unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX; +unsigned long __read_mostly tracing_max_latency; unsigned long __read_mostly tracing_thresh; /* diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 7c2e326..62a78d9 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -380,6 +380,7 @@ static void stop_irqsoff_tracer(struct trace_array *tr) static void __irqsoff_tracer_init(struct trace_array *tr) { + tracing_max_latency = 0; irqsoff_trace = tr; /* make sure that the tracer is visible */ smp_wmb(); diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 43586b6..42ae1e7 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -333,6 +333,7 @@ static void stop_wakeup_tracer(struct trace_array *tr) static int wakeup_tracer_init(struct trace_array *tr) { + tracing_max_latency = 0; wakeup_trace = tr; start_wakeup_tracer(tr); return 0; -- 1.5.6.5 --