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