forge/linux-pinenote
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

trace: better manage the context info for events

Browse source 
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.

The print routines were renamed to trace_print_context and
trace_print_lat_context, so that they can be used by tracers if they
want to use them for one of the trace_event callbacks.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2009-02-02 20:29:21 -02:00 • committed by Ingo Molnar
parent dc573f9b20
commit c4a8e8be2d
4 changed files with 151 additions and 115 deletions
Download patch file Download diff file Expand all files Collapse all files

7
kernel/trace/trace.h
View file

@ -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 *trace_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 */
};
/*