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Date: Fri, 30 Jan 2009 10:02:10 +0100
From: Frederic Weisbecker <fweisbec@...il.com>
To: Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...e.hu>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Subject: Re: [PATCH] tracing/ftrace: better manage the context info for
events
On Fri, Jan 30, 2009 at 12:59:05AM -0800, Frederic Weisbecker wrote:
> Impact: make trace_event more convenient for tracers
>
> All tracers (for the moment) that use the struct trace_event want to have
> the context info printed before their own output: the pid/cmdline, cpu, and timestamp.
>
> But some other tracers that want to implement their trace_event callbacks will
> not necessary need these information or they may want to format them as they want.
>
> This patch adds a new default-enabled trace option: TRACE_ITER_CONTEXT_INFO
> When disabled through:
>
> echo nocontext-info > /debugfs/tracing/trace_options
>
> The pid, cpu and timestamps headers will not be printed.
>
> IE with the sched_switch tracer with context-info (default):
>
> bash-2935 [001] 100.356561: 2935:120:S ==> [001] 0:140:R <idle>
> <idle>-0 [000] 100.412804: 0:140:R + [000] 11:115:S events/0
> <idle>-0 [000] 100.412816: 0:140:R ==> [000] 11:115:R events/0
> events/0-11 [000] 100.412829: 11:115:S ==> [000] 0:140:R <idle>
>
> Without context-info:
>
> 2935:120:S ==> [001] 0:140:R <idle>
> 0:140:R + [000] 11:115:S events/0
> 0:140:R ==> [000] 11:115:R events/0
> 11:115:S ==> [000] 0:140:R <idle>
>
> A tracer can disable it at runtime by clearing the bit TRACE_ITER_CONTEXT_INFO in trace_flags.
>
> Moreover, two callbacks have been added inside trace_event:
> _ context_info() which let a tracer override the format of the context info
> _ lat_context_info() which do the same with the latency_trace file
>
> If they are not defined, the usual way of printing the context info will be used.
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
> ---
> kernel/trace/trace.c | 155 ++++++++++++-------------------------------
> kernel/trace/trace.h | 7 ++-
> kernel/trace/trace_output.c | 120 +++++++++++++++++++++++++++++++++
> kernel/trace/trace_output.h | 15 ++++-
> 4 files changed, 181 insertions(+), 116 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 2f8ac1f..1516903 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -227,7 +227,7 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
>
> /* trace_flags holds trace_options default values */
> unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
> - TRACE_ITER_ANNOTATE;
> + TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO;
>
> /**
> * trace_wake_up - wake up tasks waiting for trace input
> @@ -285,6 +285,7 @@ static const char *trace_options[] = {
> "userstacktrace",
> "sym-userobj",
> "printk-msg-only",
> + "context-info",
> NULL
> };
>
> @@ -1171,7 +1172,7 @@ __find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
> }
>
> /* Find the next real entry, without updating the iterator itself */
> -static struct trace_entry *
> +struct trace_entry *
> find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
> {
> return __find_next_entry(iter, ent_cpu, ent_ts);
> @@ -1351,57 +1352,6 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
> seq_puts(m, "\n");
> }
>
> -static void
> -lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
> -{
> - int hardirq, softirq;
> - char *comm;
> -
> - comm = trace_find_cmdline(entry->pid);
> -
> - trace_seq_printf(s, "%8.8s-%-5d ", comm, entry->pid);
> - trace_seq_printf(s, "%3d", cpu);
> - trace_seq_printf(s, "%c%c",
> - (entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
> - (entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' : '.',
> - ((entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'));
> -
> - hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
> - softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
> - if (hardirq && softirq) {
> - trace_seq_putc(s, 'H');
> - } else {
> - if (hardirq) {
> - trace_seq_putc(s, 'h');
> - } else {
> - if (softirq)
> - trace_seq_putc(s, 's');
> - else
> - trace_seq_putc(s, '.');
> - }
> - }
> -
> - if (entry->preempt_count)
> - trace_seq_printf(s, "%x", entry->preempt_count);
> - else
> - trace_seq_puts(s, ".");
> -}
> -
> -unsigned long preempt_mark_thresh = 100;
> -
> -static void
> -lat_print_timestamp(struct trace_seq *s, u64 abs_usecs,
> - unsigned long rel_usecs)
> -{
> - trace_seq_printf(s, " %4lldus", abs_usecs);
> - if (rel_usecs > preempt_mark_thresh)
> - trace_seq_puts(s, "!: ");
> - else if (rel_usecs > 1)
> - trace_seq_puts(s, "+: ");
> - else
> - trace_seq_puts(s, " : ");
> -}
> -
> static void test_cpu_buff_start(struct trace_iterator *iter)
> {
> struct trace_seq *s = &iter->seq;
> @@ -1419,46 +1369,29 @@ static void test_cpu_buff_start(struct trace_iterator *iter)
> trace_seq_printf(s, "##### CPU %u buffer started ####\n", iter->cpu);
> }
>
> -static enum print_line_t
> -print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
> +static enum print_line_t print_lat_fmt(struct trace_iterator *iter)
> {
> struct trace_seq *s = &iter->seq;
> unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
> - struct trace_entry *next_entry;
> struct trace_event *event;
> - unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
> struct trace_entry *entry = iter->ent;
> - unsigned long abs_usecs;
> - unsigned long rel_usecs;
> - u64 next_ts;
> - char *comm;
> int ret;
>
> test_cpu_buff_start(iter);
>
> - next_entry = find_next_entry(iter, NULL, &next_ts);
> - if (!next_entry)
> - next_ts = iter->ts;
> - rel_usecs = ns2usecs(next_ts - iter->ts);
> - abs_usecs = ns2usecs(iter->ts - iter->tr->time_start);
> -
> - if (verbose) {
> - comm = trace_find_cmdline(entry->pid);
> - trace_seq_printf(s, "%16s %5d %3d %d %08x %08x [%08lx]"
> - " %ld.%03ldms (+%ld.%03ldms): ",
> - comm,
> - entry->pid, cpu, entry->flags,
> - entry->preempt_count, trace_idx,
> - ns2usecs(iter->ts),
> - abs_usecs/1000,
> - abs_usecs % 1000, rel_usecs/1000,
> - rel_usecs % 1000);
> - } else {
> - lat_print_generic(s, entry, cpu);
> - lat_print_timestamp(s, abs_usecs, rel_usecs);
> + event = ftrace_find_event(entry->type);
> +
> + if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
> + if (event)
> + ret = event->lat_context_info(s, entry, iter,
> + sym_flags);
> + else
> + ret = default_lat_context_info(s, entry, iter,
> + sym_flags);
> + if (ret)
> + return ret;
> }
>
> - event = ftrace_find_event(entry->type);
> if (event && event->latency_trace) {
> ret = event->latency_trace(s, entry, sym_flags);
> if (ret)
> @@ -1476,33 +1409,23 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
> unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
> struct trace_entry *entry;
> struct trace_event *event;
> - unsigned long usec_rem;
> - unsigned long long t;
> - unsigned long secs;
> - char *comm;
> int ret;
>
> entry = iter->ent;
>
> test_cpu_buff_start(iter);
>
> - comm = trace_find_cmdline(iter->ent->pid);
> -
> - t = ns2usecs(iter->ts);
> - usec_rem = do_div(t, 1000000ULL);
> - secs = (unsigned long)t;
> + event = ftrace_find_event(entry->type);
>
> - ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
> - if (!ret)
> - return TRACE_TYPE_PARTIAL_LINE;
> - ret = trace_seq_printf(s, "[%03d] ", iter->cpu);
> - if (!ret)
> - return TRACE_TYPE_PARTIAL_LINE;
> - ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
> - if (!ret)
> - return TRACE_TYPE_PARTIAL_LINE;
> + if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
> + if (event)
> + ret = event->context_info(s, entry, iter, sym_flags);
> + else
> + ret = default_context_info(s, entry, iter, sym_flags);
> + if (ret)
> + return ret;
> + }
>
> - event = ftrace_find_event(entry->type);
> if (event && event->trace) {
> ret = event->trace(s, entry, sym_flags);
> if (ret)
> @@ -1525,10 +1448,12 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
>
> entry = iter->ent;
>
> - ret = trace_seq_printf(s, "%d %d %llu ",
> - entry->pid, iter->cpu, iter->ts);
> - if (!ret)
> - return TRACE_TYPE_PARTIAL_LINE;
> + if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
> + ret = trace_seq_printf(s, "%d %d %llu ",
> + entry->pid, iter->cpu, iter->ts);
> + if (!ret)
> + return TRACE_TYPE_PARTIAL_LINE;
> + }
>
> event = ftrace_find_event(entry->type);
> if (event && event->raw) {
> @@ -1553,9 +1478,11 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
>
> entry = iter->ent;
>
> - SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
> - SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
> - SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
> + if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
> + SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
> + SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
> + SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
> + }
>
> event = ftrace_find_event(entry->type);
> if (event && event->hex)
> @@ -1575,7 +1502,7 @@ static enum print_line_t print_printk_msg_only(struct trace_iterator *iter)
>
> trace_assign_type(field, entry);
>
> - ret = trace_seq_printf(s, field->buf);
> + ret = trace_seq_printf(s, "%s", field->buf);
> if (!ret)
> return TRACE_TYPE_PARTIAL_LINE;
>
> @@ -1590,9 +1517,11 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
>
> entry = iter->ent;
>
> - SEQ_PUT_FIELD_RET(s, entry->pid);
> - SEQ_PUT_FIELD_RET(s, entry->cpu);
> - SEQ_PUT_FIELD_RET(s, iter->ts);
> + if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
> + SEQ_PUT_FIELD_RET(s, entry->pid);
> + SEQ_PUT_FIELD_RET(s, entry->cpu);
> + SEQ_PUT_FIELD_RET(s, iter->ts);
> + }
>
> event = ftrace_find_event(entry->type);
> if (event && event->binary)
> @@ -1643,7 +1572,7 @@ static enum print_line_t print_trace_line(struct trace_iterator *iter)
> return print_raw_fmt(iter);
>
> if (iter->iter_flags & TRACE_FILE_LAT_FMT)
> - return print_lat_fmt(iter, iter->idx, iter->cpu);
> + return print_lat_fmt(iter);
>
> return print_trace_fmt(iter);
> }
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index e603a29..fe251fe 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -405,6 +405,10 @@ void init_tracer_sysprof_debugfs(struct dentry *d_tracer);
>
> struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
> struct trace_array_cpu *data);
> +
> +struct trace_entry *
> +find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts);
> +
> void tracing_generic_entry_update(struct trace_entry *entry,
> unsigned long flags,
> int pc);
> @@ -591,7 +595,8 @@ enum trace_iterator_flags {
> TRACE_ITER_ANNOTATE = 0x2000,
> TRACE_ITER_USERSTACKTRACE = 0x4000,
> TRACE_ITER_SYM_USEROBJ = 0x8000,
> - TRACE_ITER_PRINTK_MSGONLY = 0x10000
> + TRACE_ITER_PRINTK_MSGONLY = 0x10000,
> + TRACE_ITER_CONTEXT_INFO = 0x20000 /* Print pid/cpu/time */
> };
>
> /*
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index 1a4e144..df5e944 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -286,6 +286,120 @@ seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
> return ret;
> }
>
> +static void
> +lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
> +{
> + int hardirq, softirq;
> + char *comm;
> +
> + comm = trace_find_cmdline(entry->pid);
> +
> + trace_seq_printf(s, "%8.8s-%-5d ", comm, entry->pid);
> + trace_seq_printf(s, "%3d", cpu);
> + trace_seq_printf(s, "%c%c",
> + (entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
> + (entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' : '.',
> + ((entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'));
> +
> + hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
> + softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
> + if (hardirq && softirq) {
> + trace_seq_putc(s, 'H');
> + } else {
> + if (hardirq) {
> + trace_seq_putc(s, 'h');
> + } else {
> + if (softirq)
> + trace_seq_putc(s, 's');
> + else
> + trace_seq_putc(s, '.');
> + }
> + }
> +
> + if (entry->preempt_count)
> + trace_seq_printf(s, "%x", entry->preempt_count);
> + else
> + trace_seq_puts(s, ".");
> +}
> +
> +static unsigned long preempt_mark_thresh = 100;
> +
> +static void
> +lat_print_timestamp(struct trace_seq *s, u64 abs_usecs,
> + unsigned long rel_usecs)
> +{
> + trace_seq_printf(s, " %4lldus", abs_usecs);
> + if (rel_usecs > preempt_mark_thresh)
> + trace_seq_puts(s, "!: ");
> + else if (rel_usecs > 1)
> + trace_seq_puts(s, "+: ");
> + else
> + trace_seq_puts(s, " : ");
> +}
> +
> +int default_context_info(struct trace_seq *s, struct trace_entry *entry,
> + struct trace_iterator *iter, int flags)
> +{
> + unsigned long usec_rem;
> + unsigned long long t;
> + unsigned long secs;
> + char *comm;
> +
> + comm = trace_find_cmdline(entry->pid);
> +
> + t = ns2usecs(iter->ts);
> + usec_rem = do_div(t, USEC_PER_SEC);
> + secs = (unsigned long)t;
> +
> + if (!trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid))
> + goto partial;
> + if (!trace_seq_printf(s, "[%03d] ", entry->cpu))
> + goto partial;
> + if (!trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem))
> + goto partial;
> +
> + return 0;
> +
> +partial:
> + return TRACE_TYPE_PARTIAL_LINE;
> +}
> +
> +int default_lat_context_info(struct trace_seq *s, struct trace_entry *entry,
> + struct trace_iterator *iter, int flags)
> +{
> + struct trace_entry *next_entry;
> + unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
> + unsigned long abs_usecs;
> + unsigned long rel_usecs;
> + u64 next_ts;
> + char *comm;
> +
> + next_entry = find_next_entry(iter, NULL, &next_ts);
> + if (!next_entry)
> + next_ts = iter->ts;
> + rel_usecs = ns2usecs(next_ts - iter->ts);
> + abs_usecs = ns2usecs(iter->ts - iter->tr->time_start);
> +
> + if (verbose) {
> + comm = trace_find_cmdline(entry->pid);
> + trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08lx]"
> + " %ld.%03ldms (+%ld.%03ldms): ",
> + comm,
> + entry->pid, entry->cpu, entry->flags,
> + entry->preempt_count, iter->idx,
> + ns2usecs(iter->ts),
> + abs_usecs/1000,
> + abs_usecs % 1000, rel_usecs/1000,
> + rel_usecs % 1000);
> + } else {
> + lat_print_generic(s, entry, entry->cpu);
> + lat_print_timestamp(s, abs_usecs, rel_usecs);
> + }
> +
> + return 0;
> +}
> +
> +
> static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
>
> static int task_state_char(unsigned long state)
> @@ -346,6 +460,12 @@ int register_ftrace_event(struct trace_event *event)
> WARN_ON(1);
> }
>
> + if (!event->context_info)
> + event->context_info = default_context_info;
> +
> + if (!event->lat_context_info)
> + event->lat_context_info = default_lat_context_info;
> +
> if (ftrace_find_event(event->type))
> goto out;
>
> diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h
> index 1cbab5e..8e8212a 100644
> --- a/kernel/trace/trace_output.h
> +++ b/kernel/trace/trace_output.h
> @@ -6,14 +6,20 @@
> typedef int (*trace_print_func)(struct trace_seq *s, struct trace_entry *entry,
> int flags);
>
> +typedef int (*context_info_func)(struct trace_seq *s,
> + struct trace_entry *entry,
> + struct trace_iterator *iter, int flags);
> +
> struct trace_event {
> struct hlist_node node;
> int type;
> - trace_print_func trace;
> - trace_print_func latency_trace;
> + trace_print_func trace; /* Usual output on trace or trace_pipe */
> + trace_print_func latency_trace; /* Through latency_trace file */
> trace_print_func raw;
> trace_print_func hex;
> trace_print_func binary;
> + context_info_func context_info; /* pid/cpu/time on line start */
> + context_info_func lat_context_info; /* same in latency_trace */
> };
>
> extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
> @@ -33,6 +39,11 @@ int seq_print_userip_objs(const struct userstack_entry *entry,
> int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
> unsigned long ip, unsigned long sym_flags);
>
> +int default_context_info(struct trace_seq *s, struct trace_entry *entry,
> + struct trace_iterator *iter, int flags);
> +int default_lat_context_info(struct trace_seq *s, struct trace_entry *entry,
> + struct trace_iterator *iter, int flags);
> +
> struct trace_event *ftrace_find_event(int type);
> int register_ftrace_event(struct trace_event *event);
> int unregister_ftrace_event(struct trace_event *event);
> --
> 1.6.1
>
>
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