linux-kernel - Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI

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Message-ID: <20110623110706.GE10238@sun>
Date:	Thu, 23 Jun 2011 15:07:06 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Don Zickus <dzickus@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Lin Ming <ming.m.lin@...el.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Vince Weaver <vweaver1@...s.utk.edu>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI_WATCHDOG event v2

On Thu, Jun 23, 2011 at 01:54:39PM +0400, Cyrill Gorcunov wrote:
...
> > 
> > No new hidden event, just a x86_pmu + a per-arch callbacks.
> 
> Looks quite good for me, Don? (i'll cook some draft patch for review meanwhile).
> 
> 	Cyrill

Since we are going to make __weak linking anyway maybe something like below
fit even beter? (untested)

	Cyrill
---
 arch/x86/kernel/cpu/perf_event_p4.c |   26 ++++++++++++++++++++++++++
 kernel/watchdog.c                   |    3 +++
 2 files changed, 29 insertions(+)

Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event_p4.c
+++ linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
@@ -705,6 +705,32 @@ static int p4_validate_raw_event(struct 
 	return 0;
 }
 
+void hw_nmi_watchdog_set_attr(struct perf_event_attr *wd_attr)
+{
+	/*
+	 * Watchdog ticks are special on Netburst, we use
+	 * that named "non-sleeping" ticks as recommended
+	 * by Intel SDM Vol3b.
+	 */
+	if (wd_attr->type	!= PERF_TYPE_HARDWARE ||
+	   wd_attr->attr.config	!= PERF_COUNT_HW_CPU_CYCLES)
+		return;
+
+	wd_attr->type	= PERF_TYPE_RAW;
+	wd_attr->config	=
+		p4_config_pack_escr(P4_ESCR_EVENT(P4_EVENT_EXECUTION_EVENT)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, NBOGUS0)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, NBOGUS1)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, NBOGUS2)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, NBOGUS3)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, BOGUS0)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, BOGUS1)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, BOGUS2)		|
+			P4_ESCR_EMASK_BIT(P4_EVENT_EXECUTION_EVENT, BOGUS3))		|
+		p4_config_pack_cccr(P4_CCCR_THRESHOLD(15) | P4_CCCR_COMPLEMENT		|
+			P4_CCCR_COMPARE);
+}
+
 static int p4_hw_config(struct perf_event *event)
 {
 	int cpu = get_cpu();
Index: linux-2.6.git/kernel/watchdog.c
===================================================================
--- linux-2.6.git.orig/kernel/watchdog.c
+++ linux-2.6.git/kernel/watchdog.c
@@ -355,6 +355,8 @@ static int watchdog(void *unused)
 
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
+void __weak hw_nmi_watchdog_set_attr(struct perf_event_attr *wd_attr) { }
+
 static int watchdog_nmi_enable(int cpu)
 {
 	struct perf_event_attr *wd_attr;
@@ -371,6 +373,7 @@ static int watchdog_nmi_enable(int cpu)
 	/* Try to register using hardware perf events */
 	wd_attr = &wd_hw_attr;
 	wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
+	hw_nmi_watchdog_set_attr(wd_attr);
 	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
 	if (!IS_ERR(event)) {
 		printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
--
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