forked from Minki/linux
tracing: make the function profiler per cpu
Impact: speed enhancement By making the function profiler record in per cpu data we not only get better readings, avoid races, we also do not have to take any locks. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This commit is contained in:
Steven Rostedt
parent
0706f1c48c
commit
cafb168a1c
@ -257,28 +257,28 @@ struct ftrace_profile_page {
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struct ftrace_profile records[];
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};
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struct ftrace_profile_stat {
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atomic_t disabled;
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struct hlist_head *hash;
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struct ftrace_profile_page *pages;
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struct ftrace_profile_page *start;
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struct tracer_stat stat;
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};
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#define PROFILE_RECORDS_SIZE \
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(PAGE_SIZE - offsetof(struct ftrace_profile_page, records))
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#define PROFILES_PER_PAGE \
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(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
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/* TODO: make these percpu, to prevent cache line bouncing */
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static struct ftrace_profile_page *profile_pages_start;
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static struct ftrace_profile_page *profile_pages;
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static struct hlist_head *ftrace_profile_hash;
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static int ftrace_profile_bits;
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static int ftrace_profile_enabled;
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static DEFINE_MUTEX(ftrace_profile_lock);
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static DEFINE_PER_CPU(atomic_t, ftrace_profile_disable);
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static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
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#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
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static raw_spinlock_t ftrace_profile_rec_lock =
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(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
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static void *
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function_stat_next(void *v, int idx)
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{
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@ -303,7 +303,13 @@ function_stat_next(void *v, int idx)
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static void *function_stat_start(struct tracer_stat *trace)
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{
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return function_stat_next(&profile_pages_start->records[0], 0);
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struct ftrace_profile_stat *stat =
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container_of(trace, struct ftrace_profile_stat, stat);
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if (!stat || !stat->start)
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return NULL;
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return function_stat_next(&stat->start->records[0], 0);
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}
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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@ -374,20 +380,11 @@ static int function_stat_show(struct seq_file *m, void *v)
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return 0;
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}
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static struct tracer_stat function_stats = {
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.name = "functions",
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.stat_start = function_stat_start,
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.stat_next = function_stat_next,
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.stat_cmp = function_stat_cmp,
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.stat_headers = function_stat_headers,
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.stat_show = function_stat_show
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};
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static void ftrace_profile_reset(void)
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static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
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{
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struct ftrace_profile_page *pg;
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pg = profile_pages = profile_pages_start;
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pg = stat->pages = stat->start;
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while (pg) {
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memset(pg->records, 0, PROFILE_RECORDS_SIZE);
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@ -395,24 +392,24 @@ static void ftrace_profile_reset(void)
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pg = pg->next;
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}
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memset(ftrace_profile_hash, 0,
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memset(stat->hash, 0,
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FTRACE_PROFILE_HASH_SIZE * sizeof(struct hlist_head));
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}
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int ftrace_profile_pages_init(void)
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int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
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{
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struct ftrace_profile_page *pg;
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int i;
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/* If we already allocated, do nothing */
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if (profile_pages)
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if (stat->pages)
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return 0;
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profile_pages = (void *)get_zeroed_page(GFP_KERNEL);
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if (!profile_pages)
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stat->pages = (void *)get_zeroed_page(GFP_KERNEL);
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if (!stat->pages)
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return -ENOMEM;
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pg = profile_pages_start = profile_pages;
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pg = stat->start = stat->pages;
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/* allocate 10 more pages to start */
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for (i = 0; i < 10; i++) {
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@ -430,13 +427,16 @@ int ftrace_profile_pages_init(void)
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return 0;
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}
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static int ftrace_profile_init(void)
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static int ftrace_profile_init_cpu(int cpu)
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{
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struct ftrace_profile_stat *stat;
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int size;
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if (ftrace_profile_hash) {
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stat = &per_cpu(ftrace_profile_stats, cpu);
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if (stat->hash) {
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/* If the profile is already created, simply reset it */
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ftrace_profile_reset();
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ftrace_profile_reset(stat);
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return 0;
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}
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@ -446,29 +446,45 @@ static int ftrace_profile_init(void)
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*/
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size = FTRACE_PROFILE_HASH_SIZE;
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ftrace_profile_hash =
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kzalloc(sizeof(struct hlist_head) * size, GFP_KERNEL);
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stat->hash = kzalloc(sizeof(struct hlist_head) * size, GFP_KERNEL);
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if (!ftrace_profile_hash)
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if (!stat->hash)
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return -ENOMEM;
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if (!ftrace_profile_bits) {
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size--;
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for (; size; size >>= 1)
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ftrace_profile_bits++;
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}
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/* Preallocate a few pages */
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if (ftrace_profile_pages_init() < 0) {
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kfree(ftrace_profile_hash);
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ftrace_profile_hash = NULL;
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if (ftrace_profile_pages_init(stat) < 0) {
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kfree(stat->hash);
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stat->hash = NULL;
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return -ENOMEM;
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}
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return 0;
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}
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static int ftrace_profile_init(void)
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{
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int cpu;
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int ret = 0;
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for_each_online_cpu(cpu) {
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ret = ftrace_profile_init_cpu(cpu);
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if (ret)
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break;
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}
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return ret;
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}
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/* interrupts must be disabled */
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static struct ftrace_profile *ftrace_find_profiled_func(unsigned long ip)
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static struct ftrace_profile *
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ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
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{
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struct ftrace_profile *rec;
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struct hlist_head *hhd;
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@ -476,7 +492,7 @@ static struct ftrace_profile *ftrace_find_profiled_func(unsigned long ip)
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unsigned long key;
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key = hash_long(ip, ftrace_profile_bits);
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hhd = &ftrace_profile_hash[key];
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hhd = &stat->hash[key];
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if (hlist_empty(hhd))
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return NULL;
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@ -489,52 +505,50 @@ static struct ftrace_profile *ftrace_find_profiled_func(unsigned long ip)
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return NULL;
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}
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static void ftrace_add_profile(struct ftrace_profile *rec)
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static void ftrace_add_profile(struct ftrace_profile_stat *stat,
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struct ftrace_profile *rec)
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{
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unsigned long key;
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key = hash_long(rec->ip, ftrace_profile_bits);
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hlist_add_head_rcu(&rec->node, &ftrace_profile_hash[key]);
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hlist_add_head_rcu(&rec->node, &stat->hash[key]);
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}
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/* Interrupts must be disabled calling this */
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static struct ftrace_profile *
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ftrace_profile_alloc(unsigned long ip, bool alloc_safe)
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ftrace_profile_alloc(struct ftrace_profile_stat *stat,
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unsigned long ip, bool alloc_safe)
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{
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struct ftrace_profile *rec = NULL;
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/* prevent recursion */
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if (atomic_inc_return(&__get_cpu_var(ftrace_profile_disable)) != 1)
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if (atomic_inc_return(&stat->disabled) != 1)
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goto out;
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__raw_spin_lock(&ftrace_profile_rec_lock);
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/* Try to always keep another page available */
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if (!profile_pages->next && alloc_safe)
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profile_pages->next = (void *)get_zeroed_page(GFP_ATOMIC);
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if (!stat->pages->next && alloc_safe)
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stat->pages->next = (void *)get_zeroed_page(GFP_ATOMIC);
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/*
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* Try to find the function again since another
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* task on another CPU could have added it
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*/
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rec = ftrace_find_profiled_func(ip);
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rec = ftrace_find_profiled_func(stat, ip);
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if (rec)
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goto out_unlock;
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goto out;
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if (profile_pages->index == PROFILES_PER_PAGE) {
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if (!profile_pages->next)
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goto out_unlock;
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profile_pages = profile_pages->next;
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if (stat->pages->index == PROFILES_PER_PAGE) {
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if (!stat->pages->next)
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goto out;
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stat->pages = stat->pages->next;
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}
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rec = &profile_pages->records[profile_pages->index++];
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rec = &stat->pages->records[stat->pages->index++];
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rec->ip = ip;
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ftrace_add_profile(rec);
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ftrace_add_profile(stat, rec);
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out_unlock:
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__raw_spin_unlock(&ftrace_profile_rec_lock);
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out:
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atomic_dec(&__get_cpu_var(ftrace_profile_disable));
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atomic_dec(&stat->disabled);
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return rec;
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}
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@ -552,6 +566,7 @@ static bool ftrace_safe_to_allocate(void)
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static void
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function_profile_call(unsigned long ip, unsigned long parent_ip)
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{
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struct ftrace_profile_stat *stat;
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struct ftrace_profile *rec;
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unsigned long flags;
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bool alloc_safe;
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@ -562,9 +577,14 @@ function_profile_call(unsigned long ip, unsigned long parent_ip)
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alloc_safe = ftrace_safe_to_allocate();
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local_irq_save(flags);
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rec = ftrace_find_profiled_func(ip);
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stat = &__get_cpu_var(ftrace_profile_stats);
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if (!stat->hash)
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goto out;
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rec = ftrace_find_profiled_func(stat, ip);
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if (!rec) {
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rec = ftrace_profile_alloc(ip, alloc_safe);
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rec = ftrace_profile_alloc(stat, ip, alloc_safe);
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if (!rec)
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goto out;
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}
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@ -583,13 +603,19 @@ static int profile_graph_entry(struct ftrace_graph_ent *trace)
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static void profile_graph_return(struct ftrace_graph_ret *trace)
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{
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unsigned long flags;
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struct ftrace_profile_stat *stat;
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struct ftrace_profile *rec;
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unsigned long flags;
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local_irq_save(flags);
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rec = ftrace_find_profiled_func(trace->func);
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stat = &__get_cpu_var(ftrace_profile_stats);
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if (!stat->hash)
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goto out;
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rec = ftrace_find_profiled_func(stat, trace->func);
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if (rec)
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rec->time += trace->rettime - trace->calltime;
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out:
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local_irq_restore(flags);
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}
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@ -687,17 +713,52 @@ static const struct file_operations ftrace_profile_fops = {
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.write = ftrace_profile_write,
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};
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/* used to initialize the real stat files */
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static struct tracer_stat function_stats __initdata = {
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.name = "functions",
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.stat_start = function_stat_start,
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.stat_next = function_stat_next,
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.stat_cmp = function_stat_cmp,
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.stat_headers = function_stat_headers,
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.stat_show = function_stat_show
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};
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static void ftrace_profile_debugfs(struct dentry *d_tracer)
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{
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struct ftrace_profile_stat *stat;
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struct dentry *entry;
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char *name;
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int ret;
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int cpu;
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ret = register_stat_tracer(&function_stats);
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if (ret) {
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pr_warning("Warning: could not register "
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"function stats\n");
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for_each_possible_cpu(cpu) {
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stat = &per_cpu(ftrace_profile_stats, cpu);
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/* allocate enough for function name + cpu number */
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name = kmalloc(32, GFP_KERNEL);
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if (!name) {
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/*
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* The files created are permanent, if something happens
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* we still do not free memory.
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*/
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kfree(stat);
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WARN(1,
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"Could not allocate stat file for cpu %d\n",
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cpu);
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return;
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}
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stat->stat = function_stats;
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snprintf(name, 32, "function%d", cpu);
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stat->stat.name = name;
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ret = register_stat_tracer(&stat->stat);
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if (ret) {
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WARN(1,
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"Could not register function stat for cpu %d\n",
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cpu);
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kfree(name);
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return;
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}
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}
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entry = debugfs_create_file("function_profile_enabled", 0644,
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d_tracer, NULL, &ftrace_profile_fops);
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