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perf_counter tools: Add locking to perf top

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perf_counter tools: Add locking to perf top

We need to protect the active_symbols list as two threads change it:
the main thread adding entries to the head and the display thread
decaying entries from any place in the list.

Also related: take a snapshot of syme->count[0] before using it to
calculate the weight and to show the same number used in this calc when
displaying the symbol usage.

Reported-by: Mike Galbraith <efault@gmx.de>
Tested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090529200307.GR4747@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arnaldo Carvalho de Melo 2009-05-29 17:03:07 -03:00 committed by Ingo Molnar
parent b78c07d45a
commit c44613a4c1
1 changed files with 31 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
Documentation/perf_counter/builtin-top.c
View File

@ -129,6 +129,8 @@ struct sym_entry {
struct rb_node rb_node;
struct list_head node;
unsigned long count[MAX_COUNTERS];
unsigned long snap_count;
double weight;
int skip;
};
@ -141,17 +143,16 @@ struct dso *kernel_dso;
* after decayed.
*/
static LIST_HEAD(active_symbols);
static pthread_mutex_t active_symbols_lock = PTHREAD_MUTEX_INITIALIZER;
/*
* Ordering weight: count-1 * count-2 * ... / count-n
*/
static double sym_weight(const struct sym_entry *sym)
{
double weight;
double weight = sym->snap_count;
int counter;
weight = sym->count[0];
for (counter = 1; counter < nr_counters-1; counter++)
weight *= sym->count[counter];
@ -164,11 +165,18 @@ static long events;
static long userspace_events;
static const char CONSOLE_CLEAR[] = "";
static void list_insert_active_sym(struct sym_entry *syme)
static void __list_insert_active_sym(struct sym_entry *syme)
{
list_add(&syme->node, &active_symbols);
}
static void list_remove_active_sym(struct sym_entry *syme)
{
pthread_mutex_lock(&active_symbols_lock);
list_del_init(&syme->node);
pthread_mutex_unlock(&active_symbols_lock);
}
static void rb_insert_active_sym(struct rb_root *tree, struct sym_entry *se)
{
struct rb_node **p = &tree->rb_node;
@ -179,7 +187,7 @@ static void rb_insert_active_sym(struct rb_root *tree, struct sym_entry *se)
parent = *p;
iter = rb_entry(parent, struct sym_entry, rb_node);
if (sym_weight(se) > sym_weight(iter))
if (se->weight > iter->weight)
p = &(*p)->rb_left;
else
p = &(*p)->rb_right;
@ -203,15 +211,21 @@ static void print_sym_table(void)
events = userspace_events = 0;
/* Sort the active symbols */
list_for_each_entry_safe(syme, n, &active_symbols, node) {
if (syme->count[0] != 0) {
pthread_mutex_lock(&active_symbols_lock);
syme = list_entry(active_symbols.next, struct sym_entry, node);
pthread_mutex_unlock(&active_symbols_lock);
list_for_each_entry_safe_from(syme, n, &active_symbols, node) {
syme->snap_count = syme->count[0];
if (syme->snap_count != 0) {
syme->weight = sym_weight(syme);
rb_insert_active_sym(&tmp, syme);
sum_kevents += syme->count[0];
sum_kevents += syme->snap_count;
for (j = 0; j < nr_counters; j++)
syme->count[j] = zero ? 0 : syme->count[j] * 7 / 8;
} else
list_del_init(&syme->node);
list_remove_active_sym(syme);
}
write(1, CONSOLE_CLEAR, strlen(CONSOLE_CLEAR));
@ -264,19 +278,18 @@ static void print_sym_table(void)
struct symbol *sym = (struct symbol *)(syme + 1);
float pcnt;
if (++printed > 18 || syme->count[0] < count_filter)
break;
if (++printed > 18 || syme->snap_count < count_filter)
continue;
pcnt = 100.0 - (100.0 * ((sum_kevents - syme->count[0]) /
pcnt = 100.0 - (100.0 * ((sum_kevents - syme->snap_count) /
sum_kevents));
if (nr_counters == 1)
printf("%19.2f - %4.1f%% - %016llx : %s\n",
sym_weight(syme),
pcnt, sym->start, sym->name);
syme->weight, pcnt, sym->start, sym->name);
else
printf("%8.1f %10ld - %4.1f%% - %016llx : %s\n",
sym_weight(syme), syme->count[0],
syme->weight, syme->snap_count,
pcnt, sym->start, sym->name);
}
@ -395,8 +408,10 @@ static void record_ip(uint64_t ip, int counter)
if (!syme->skip) {
syme->count[counter]++;
pthread_mutex_lock(&active_symbols_lock);
if (list_empty(&syme->node) || !syme->node.next)
list_insert_active_sym(syme);
__list_insert_active_sym(syme);
pthread_mutex_unlock(&active_symbols_lock);
return;
}
}