Let's group some values together. This avoids a too detailed
histogram. Some sort of logarythmic scale could be useful
for latency plots.
Now we can write something like:
'hist:key=latency.bucket:val=hitcount:sort=latency'
latency: 0 hitcount: 166440
latency: 256 hitcount: 21104
latency: 512 hitcount: 7754
latency: 768 hitcount: 3269
latency: 1024 hitcount: 1647
latency: 1280 hitcount: 841
latency: 1536 hitcount: 524
latency: 1792 hitcount: 371
latency: 2048 hitcount: 302
latency: 2304 hitcount: 240
latency: 2560 hitcount: 207
latency: 2816 hitcount: 149
latency: 3072 hitcount: 123
latency: 3328 hitcount: 119
latency: 3584 hitcount: 102
latency: 3840 hitcount: 94
latency: 4096 hitcount: 89
latency: 4352 hitcount: 79
latency: 4608 hitcount: 88
One thing I struggled with the grammatic above is that I haven't found
a nice way to pass in arguments, for example the bucket size. There a lot
of options to do it. Just a couple random ideas, not necessarly consistent
or clever:
'hist:key=latency.bucket[10,1.5]:val=hitcount:sort=latency'
where [x,y]: x first bucket size, y scaling factor
'hist:key=latency:val=hitcount:sort=latency:bucket=latency,10,1.5'
Not for inclusion!
Not-Signed-off-by: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>
---
kernel/trace/trace_events_hist.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index fe06707..cac94a6 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -84,6 +84,7 @@ enum hist_field_flags {
HIST_FIELD_STRING = 8,
HIST_FIELD_EXECNAME = 16,
HIST_FIELD_SYSCALL = 32,
+ HIST_FIELD_BUCKET = 64,
};
struct hist_trigger_sort_key {
@@ -400,6 +401,8 @@ static int create_key_field(struct hist_trigger_data *hist_data,
flags |= HIST_FIELD_EXECNAME;
else if (!strcmp(field_str, "syscall"))
flags |= HIST_FIELD_SYSCALL;
+ else if (!strcmp(field_str, "bucket"))
+ flags |= HIST_FIELD_BUCKET;
}
field = trace_find_event_field(file->event_call, field_name);
@@ -900,6 +903,9 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec)
key = entries;
} else {
field_contents = hist_data->key->fn(hist_data->key, rec);
+ if (hist_data->key->flags & HIST_FIELD_BUCKET)
+ field_contents &= ~0xff;
+
if (hist_data->key->flags & HIST_FIELD_STRING)
key = (void *)field_contents;
else
@@ -1343,6 +1349,8 @@ static const char *get_hist_field_flags(struct hist_field *hist_field)
flags_str = "hex";
else if (hist_field->flags & HIST_FIELD_SYSCALL)
flags_str = "syscall";
+ else if (hist_field->flags & HIST_FIELD_BUCKET)
+ flags_str = "bucket";
else if (hist_field->flags & HIST_FIELD_EXECNAME)
flags_str = "execname";
--
2.1.0
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