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Subject[PATCH 6/7] perf: Humanize the number of contexts
Date
Instead of hardcoding the number of contexts for the recursions
barriers, define a cpp constant to make the code more
self-explanatory.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
---
include/linux/perf_event.h | 14 ++++++++------
kernel/perf_event.c | 4 ++--
kernel/trace/trace_event_perf.c | 8 ++++----
3 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index d7e8ea6..ae6fa60 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -808,6 +808,12 @@ struct perf_event_context {
struct rcu_head rcu_head;
};

+/*
+ * Number of contexts where an event can trigger:
+ * task, softirq, hardirq, nmi.
+ */
+#define PERF_NR_CONTEXTS 4
+
/**
* struct perf_event_cpu_context - per cpu event context structure
*/
@@ -821,12 +827,8 @@ struct perf_cpu_context {
struct mutex hlist_mutex;
int hlist_refcount;

- /*
- * Recursion avoidance:
- *
- * task, softirq, irq, nmi context
- */
- int recursion[4];
+ /* Recursion avoidance in each contexts */
+ int recursion[PERF_NR_CONTEXTS];
};

struct perf_output_handle {
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 75ab8a2..f416aef 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1772,7 +1772,7 @@ struct callchain_cpus_entries {
struct perf_callchain_entry *cpu_entries[0];
};

-static DEFINE_PER_CPU(int, callchain_recursion[4]);
+static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
static atomic_t nr_callchain_events;
static DEFINE_MUTEX(callchain_mutex);
struct callchain_cpus_entries *callchain_cpus_entries;
@@ -1828,7 +1828,7 @@ static int alloc_callchain_buffers(void)
if (!entries)
return -ENOMEM;

- size = sizeof(struct perf_callchain_entry) * 4;
+ size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;

for_each_possible_cpu(cpu) {
entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 000e6e8..db2eae2 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -9,7 +9,7 @@
#include <linux/kprobes.h>
#include "trace.h"

-static char *perf_trace_buf[4];
+static char *perf_trace_buf[PERF_NR_CONTEXTS];

/*
* Force it to be aligned to unsigned long to avoid misaligned accesses
@@ -45,7 +45,7 @@ static int perf_trace_event_init(struct ftrace_event_call *tp_event,
char *buf;
int i;

- for (i = 0; i < 4; i++) {
+ for (i = 0; i < PERF_NR_CONTEXTS; i++) {
buf = (char *)alloc_percpu(perf_trace_t);
if (!buf)
goto fail;
@@ -65,7 +65,7 @@ fail:
if (!total_ref_count) {
int i;

- for (i = 0; i < 4; i++) {
+ for (i = 0; i < PERF_NR_CONTEXTS; i++) {
free_percpu(perf_trace_buf[i]);
perf_trace_buf[i] = NULL;
}
@@ -140,7 +140,7 @@ void perf_trace_destroy(struct perf_event *p_event)
tp_event->perf_events = NULL;

if (!--total_ref_count) {
- for (i = 0; i < 4; i++) {
+ for (i = 0; i < PERF_NR_CONTEXTS; i++) {
free_percpu(perf_trace_buf[i]);
perf_trace_buf[i] = NULL;
}
--
1.6.2.3


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