Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755396AbZCEP3l (ORCPT ); Thu, 5 Mar 2009 10:29:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753000AbZCEP3d (ORCPT ); Thu, 5 Mar 2009 10:29:33 -0500 Received: from mga09.intel.com ([134.134.136.24]:14306 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753135AbZCEP3c (ORCPT ); Thu, 5 Mar 2009 10:29:32 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.38,307,1233561600"; d="scan'208";a="391939730" Date: Thu, 5 Mar 2009 16:29:21 +0100 From: Markus Metzger To: linux-kernel@vger.kernel.org, mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com Cc: markus.t.metzger@intel.com, markus.t.metzger@gmail.com, roland@redhat.com, eranian@googlemail.com, oleg@redhat.com, juan.villacis@intel.com, ak@linux.jf.intel.com, srostedt@redhat.com Subject: [patch 3/4] x86, hw-branch-tracer: keep resources on stop Message-ID: <20090305162921.A25216@sedona.ch.intel.com> Mime-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.2.5i Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5661 Lines: 209 Distinguish init/reset and start/stop: init/reset will allocate and release bts tracing resources stop/start will suspend and resume bts tracing Return an error on init() if no cpu can be traced. Signed-off-by: Markus Metzger --- Index: gits/kernel/trace/trace_hw_branches.c =================================================================== --- gits.orig/kernel/trace/trace_hw_branches.c 2009-03-02 16:15:11.000000000 +0100 +++ gits/kernel/trace/trace_hw_branches.c 2009-03-03 10:17:31.000000000 +0100 @@ -38,17 +38,18 @@ static DEFINE_PER_CPU(unsigned char[SIZE #define this_tracer per_cpu(tracer, smp_processor_id()) #define this_buffer per_cpu(buffer, smp_processor_id()) -static int __read_mostly trace_hw_branches_enabled; +static int trace_hw_branches_enabled __read_mostly; +static int trace_hw_branches_suspended __read_mostly; static struct trace_array *hw_branch_trace __read_mostly; /* - * Start tracing on the current cpu. + * Initialize the tracer for the current cpu. * The argument is ignored. * * pre: bts_tracer_lock must be locked. */ -static void bts_trace_start_cpu(void *arg) +static void bts_trace_init_cpu(void *arg) { if (this_tracer) ds_release_bts(this_tracer); @@ -63,23 +64,39 @@ static void bts_trace_start_cpu(void *ar } } -static void bts_trace_start(struct trace_array *tr) +static int bts_trace_init(struct trace_array *tr) { + int cpu, avail; + spin_lock(&bts_tracer_lock); - on_each_cpu(bts_trace_start_cpu, NULL, 1); - trace_hw_branches_enabled = 1; + hw_branch_trace = tr; + + on_each_cpu(bts_trace_init_cpu, NULL, 1); + + /* Check on how many cpus we could enable tracing */ + avail = 0; + for_each_online_cpu(cpu) + if (per_cpu(tracer, cpu)) + avail++; + + trace_hw_branches_enabled = (avail ? 1 : 0); + trace_hw_branches_suspended = 0; spin_unlock(&bts_tracer_lock); + + + /* If we could not enable tracing on a single cpu, we fail. */ + return avail ? 0 : -EOPNOTSUPP; } /* - * Stop tracing on the current cpu. + * Release the tracer for the current cpu. * The argument is ignored. * * pre: bts_tracer_lock must be locked. */ -static void bts_trace_stop_cpu(void *arg) +static void bts_trace_release_cpu(void *arg) { if (this_tracer) { ds_release_bts(this_tracer); @@ -87,12 +104,57 @@ static void bts_trace_stop_cpu(void *arg } } -static void bts_trace_stop(struct trace_array *tr) +static void bts_trace_reset(struct trace_array *tr) { spin_lock(&bts_tracer_lock); + on_each_cpu(bts_trace_release_cpu, NULL, 1); trace_hw_branches_enabled = 0; - on_each_cpu(bts_trace_stop_cpu, NULL, 1); + trace_hw_branches_suspended = 0; + + spin_unlock(&bts_tracer_lock); +} + +/* + * Resume tracing on the current cpu. + * The argument is ignored. + * + * pre: bts_tracer_lock must be locked. + */ +static void bts_trace_resume_cpu(void *arg) +{ + if (this_tracer) + ds_resume_bts(this_tracer); +} + +static void bts_trace_start(struct trace_array *tr) +{ + spin_lock(&bts_tracer_lock); + + on_each_cpu(bts_trace_resume_cpu, NULL, 1); + trace_hw_branches_suspended = 0; + + spin_unlock(&bts_tracer_lock); +} + +/* + * Suspend tracing on the current cpu. + * The argument is ignored. + * + * pre: bts_tracer_lock must be locked. + */ +static void bts_trace_suspend_cpu(void *arg) +{ + if (this_tracer) + ds_suspend_bts(this_tracer); +} + +static void bts_trace_stop(struct trace_array *tr) +{ + spin_lock(&bts_tracer_lock); + + on_each_cpu(bts_trace_suspend_cpu, NULL, 1); + trace_hw_branches_suspended = 1; spin_unlock(&bts_tracer_lock); } @@ -110,10 +172,14 @@ static int __cpuinit bts_hotcpu_handler( switch (action) { case CPU_ONLINE: case CPU_DOWN_FAILED: - smp_call_function_single(cpu, bts_trace_start_cpu, NULL, 1); + smp_call_function_single(cpu, bts_trace_init_cpu, NULL, 1); + + if (trace_hw_branches_suspended) + smp_call_function_single(cpu, bts_trace_suspend_cpu, + NULL, 1); break; case CPU_DOWN_PREPARE: - smp_call_function_single(cpu, bts_trace_stop_cpu, NULL, 1); + smp_call_function_single(cpu, bts_trace_release_cpu, NULL, 1); break; } @@ -126,20 +192,6 @@ static struct notifier_block bts_hotcpu_ .notifier_call = bts_hotcpu_handler }; -static int bts_trace_init(struct trace_array *tr) -{ - hw_branch_trace = tr; - - bts_trace_start(tr); - - return 0; -} - -static void bts_trace_reset(struct trace_array *tr) -{ - bts_trace_stop(tr); -} - static void bts_trace_print_header(struct seq_file *m) { seq_puts(m, "# CPU# TO <- FROM\n"); @@ -276,7 +328,8 @@ void trace_hw_branch_oops(void) { spin_lock(&bts_tracer_lock); - trace_bts_cpu(hw_branch_trace); + if (trace_hw_branches_enabled) + trace_bts_cpu(hw_branch_trace); spin_unlock(&bts_tracer_lock); } --------------------------------------------------------------------- Intel GmbH Dornacher Strasse 1 85622 Feldkirchen/Muenchen Germany Sitz der Gesellschaft: Feldkirchen bei Muenchen Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes Schwaderer Registergericht: Muenchen HRB 47456 Ust.-IdNr. 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