diff options
author | Ingo Molnar | 2009-06-05 16:50:29 +0200 |
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committer | Ingo Molnar | 2009-06-05 16:50:29 +0200 |
commit | 918143e8b7d6153d7a83a3f854323407939f4a7e (patch) | |
tree | 34c0b1434516d146fc3811a6d071b052dd59342b /kernel/trace | |
parent | 64edbc562034f2ec3fce382cb208fab40586d005 (diff) | |
parent | 563af16c30ede41eda2d614195d88e07f7c7103d (diff) |
Merge branch 'tip/tracing/ftrace-4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace
Diffstat (limited to 'kernel/trace')
-rw-r--r-- | kernel/trace/ring_buffer.c | 104 | ||||
-rw-r--r-- | kernel/trace/trace_output.c | 35 | ||||
-rw-r--r-- | kernel/trace/trace_stack.c | 2 |
3 files changed, 81 insertions, 60 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 16b24d49604c..7102d7a2fadb 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -370,6 +370,9 @@ static inline int test_time_stamp(u64 delta) /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) +/* Max number of timestamps that can fit on a page */ +#define RB_TIMESTAMPS_PER_PAGE (BUF_PAGE_SIZE / RB_LEN_TIME_STAMP) + int ring_buffer_print_page_header(struct trace_seq *s) { struct buffer_data_page field; @@ -1335,6 +1338,38 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, return event; } +static inline int +rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, + struct ring_buffer_event *event) +{ + unsigned long new_index, old_index; + struct buffer_page *bpage; + unsigned long index; + unsigned long addr; + + new_index = rb_event_index(event); + old_index = new_index + rb_event_length(event); + addr = (unsigned long)event; + addr &= PAGE_MASK; + + bpage = cpu_buffer->tail_page; + + if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { + /* + * This is on the tail page. It is possible that + * a write could come in and move the tail page + * and write to the next page. That is fine + * because we just shorten what is on this page. + */ + index = local_cmpxchg(&bpage->write, old_index, new_index); + if (index == old_index) + return 1; + } + + /* could not discard */ + return 0; +} + static int rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, u64 *delta) @@ -1377,17 +1412,24 @@ rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, event->array[0] = *delta >> TS_SHIFT; } else { cpu_buffer->commit_page->page->time_stamp = *ts; - event->time_delta = 0; - event->array[0] = 0; + /* try to discard, since we do not need this */ + if (!rb_try_to_discard(cpu_buffer, event)) { + /* nope, just zero it */ + event->time_delta = 0; + event->array[0] = 0; + } } cpu_buffer->write_stamp = *ts; /* let the caller know this was the commit */ ret = 1; } else { - /* Darn, this is just wasted space */ - event->time_delta = 0; - event->array[0] = 0; - ret = 0; + /* Try to discard the event */ + if (!rb_try_to_discard(cpu_buffer, event)) { + /* Darn, this is just wasted space */ + event->time_delta = 0; + event->array[0] = 0; + ret = 0; + } } *delta = 0; @@ -1682,10 +1724,6 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer, struct ring_buffer_event *event) { struct ring_buffer_per_cpu *cpu_buffer; - unsigned long new_index, old_index; - struct buffer_page *bpage; - unsigned long index; - unsigned long addr; int cpu; /* The event is discarded regardless */ @@ -1701,24 +1739,8 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer, cpu = smp_processor_id(); cpu_buffer = buffer->buffers[cpu]; - new_index = rb_event_index(event); - old_index = new_index + rb_event_length(event); - addr = (unsigned long)event; - addr &= PAGE_MASK; - - bpage = cpu_buffer->tail_page; - - if (bpage == (void *)addr && rb_page_write(bpage) == old_index) { - /* - * This is on the tail page. It is possible that - * a write could come in and move the tail page - * and write to the next page. That is fine - * because we just shorten what is on this page. - */ - index = local_cmpxchg(&bpage->write, old_index, new_index); - if (index == old_index) - goto out; - } + if (!rb_try_to_discard(cpu_buffer, event)) + goto out; /* * The commit is still visible by the reader, so we @@ -2253,8 +2275,8 @@ static void rb_advance_iter(struct ring_buffer_iter *iter) * Check if we are at the end of the buffer. */ if (iter->head >= rb_page_size(iter->head_page)) { - if (RB_WARN_ON(buffer, - iter->head_page == cpu_buffer->commit_page)) + /* discarded commits can make the page empty */ + if (iter->head_page == cpu_buffer->commit_page) return; rb_inc_iter(iter); return; @@ -2297,12 +2319,10 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) /* * We repeat when a timestamp is encountered. It is possible * to get multiple timestamps from an interrupt entering just - * as one timestamp is about to be written. The max times - * that this can happen is the number of nested interrupts we - * can have. Nesting 10 deep of interrupts is clearly - * an anomaly. + * as one timestamp is about to be written, or from discarded + * commits. The most that we can have is the number on a single page. */ - if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) + if (RB_WARN_ON(cpu_buffer, ++nr_loops > RB_TIMESTAMPS_PER_PAGE)) return NULL; reader = rb_get_reader_page(cpu_buffer); @@ -2368,14 +2388,14 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) again: /* - * We repeat when a timestamp is encountered. It is possible - * to get multiple timestamps from an interrupt entering just - * as one timestamp is about to be written. The max times - * that this can happen is the number of nested interrupts we - * can have. Nesting 10 deep of interrupts is clearly - * an anomaly. + * We repeat when a timestamp is encountered. + * We can get multiple timestamps by nested interrupts or also + * if filtering is on (discarding commits). Since discarding + * commits can be frequent we can get a lot of timestamps. + * But we limit them by not adding timestamps if they begin + * at the start of a page. */ - if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) + if (RB_WARN_ON(cpu_buffer, ++nr_loops > RB_TIMESTAMPS_PER_PAGE)) return NULL; if (rb_per_cpu_empty(cpu_buffer)) diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 0fe3b223f7ed..425725c1622d 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -223,10 +223,9 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim, { unsigned long mask; const char *str; + const char *ret = p->buffer + p->len; int i; - trace_seq_init(p); - for (i = 0; flag_array[i].name && flags; i++) { mask = flag_array[i].mask; @@ -249,7 +248,7 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim, trace_seq_putc(p, 0); - return p->buffer; + return ret; } EXPORT_SYMBOL(ftrace_print_flags_seq); @@ -258,8 +257,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val, const struct trace_print_flags *symbol_array) { int i; - - trace_seq_init(p); + const char *ret = p->buffer + p->len; for (i = 0; symbol_array[i].name; i++) { @@ -275,7 +273,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val, trace_seq_putc(p, 0); - return p->buffer; + return ret; } EXPORT_SYMBOL(ftrace_print_symbols_seq); @@ -389,17 +387,20 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s, if (ip == ULONG_MAX || !ret) break; - if (i && ret) - ret = trace_seq_puts(s, " <- "); + if (ret) + ret = trace_seq_puts(s, " => "); if (!ip) { if (ret) ret = trace_seq_puts(s, "??"); + if (ret) + ret = trace_seq_puts(s, "\n"); continue; } if (!ret) break; if (ret) ret = seq_print_user_ip(s, mm, ip, sym_flags); + ret = trace_seq_puts(s, "\n"); } if (mm) @@ -975,16 +976,16 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter, trace_assign_type(field, iter->ent); + if (!trace_seq_puts(s, "<stack trace>\n")) + goto partial; for (i = 0; i < FTRACE_STACK_ENTRIES; i++) { - if (!field->caller[i]) + if (!field->caller[i] || (field->caller[i] == ULONG_MAX)) break; - if (i) { - if (!trace_seq_puts(s, " <= ")) - goto partial; + if (!trace_seq_puts(s, " => ")) + goto partial; - if (!seq_print_ip_sym(s, field->caller[i], flags)) - goto partial; - } + if (!seq_print_ip_sym(s, field->caller[i], flags)) + goto partial; if (!trace_seq_puts(s, "\n")) goto partial; } @@ -1012,10 +1013,10 @@ static enum print_line_t trace_user_stack_print(struct trace_iterator *iter, trace_assign_type(field, iter->ent); - if (!seq_print_userip_objs(field, s, flags)) + if (!trace_seq_puts(s, "<user stack trace>\n")) goto partial; - if (!trace_seq_putc(s, '\n')) + if (!seq_print_userip_objs(field, s, flags)) goto partial; return TRACE_TYPE_HANDLED; diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 1796f00524e1..2d7aebd71dbd 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -265,7 +265,7 @@ static int t_show(struct seq_file *m, void *v) seq_printf(m, " Depth Size Location" " (%d entries)\n" " ----- ---- --------\n", - max_stack_trace.nr_entries); + max_stack_trace.nr_entries - 1); if (!stack_tracer_enabled && !max_stack_size) print_disabled(m); |