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Message-ID: <20151105144334.GA28273@danjae.kornet>
Date: Thu, 5 Nov 2015 23:43:34 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Tom Zanussi <tom.zanussi@...ux.intel.com>
Cc: rostedt@...dmis.org, daniel.wagner@...-carit.de,
masami.hiramatsu.pt@...achi.com, josh@...htriplett.org,
andi@...stfloor.org, mathieu.desnoyers@...icios.com,
peterz@...radead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 00/28] tracing: 'hist' triggers
Hi Tom,
I implemented 'log2' modifier on top of your v11 patchset. Could you
please take a look at this?
>From 5fc74778b9af5e4e121a0563fb8e54e8f495ca29 Mon Sep 17 00:00:00 2001
From: Namhyung Kim <namhyung@...nel.org>
Date: Thu, 5 Nov 2015 23:34:05 +0900
Subject: [PATCH] tracing: Add hist trigger 'log2' modifier
Allow users to have numeric fields displayed as log2 values in case
value range is very wide by appending '.log2' to field names.
For example,
# echo 'hist:key=bytes_req' > kmalloc/trigger
# cat kmalloc/hist
{ bytes_req: 504 } hitcount: 1
{ bytes_req: 11 } hitcount: 1
{ bytes_req: 104 } hitcount: 1
{ bytes_req: 48 } hitcount: 1
{ bytes_req: 2048 } hitcount: 1
{ bytes_req: 4096 } hitcount: 1
{ bytes_req: 240 } hitcount: 1
{ bytes_req: 392 } hitcount: 1
{ bytes_req: 13 } hitcount: 1
{ bytes_req: 28 } hitcount: 1
{ bytes_req: 12 } hitcount: 1
{ bytes_req: 64 } hitcount: 2
{ bytes_req: 128 } hitcount: 2
{ bytes_req: 32 } hitcount: 2
{ bytes_req: 8 } hitcount: 11
{ bytes_req: 10 } hitcount: 13
{ bytes_req: 24 } hitcount: 25
{ bytes_req: 160 } hitcount: 29
{ bytes_req: 16 } hitcount: 33
{ bytes_req: 80 } hitcount: 36
When using '.log2' modifier, the output looks like:
# echo 'hist:key=bytes_req.log2' > kmalloc/trigger
# cat kmalloc/hist
{ bytes_req: ~ 2^12 } hitcount: 1
{ bytes_req: ~ 2^11 } hitcount: 1
{ bytes_req: ~ 2^9 } hitcount: 2
{ bytes_req: ~ 2^6 } hitcount: 3
{ bytes_req: ~ 2^3 } hitcount: 13
{ bytes_req: ~ 2^5 } hitcount: 19
{ bytes_req: ~ 2^8 } hitcount: 49
{ bytes_req: ~ 2^7 } hitcount: 57
{ bytes_req: ~ 2^4 } hitcount: 74
Cc: Tom Zanussi <tom.zanussi@...ux.intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
kernel/trace/trace.c | 1 +
kernel/trace/trace_events_hist.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 74f95745acbc..542486468707 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3837,6 +3837,7 @@ static const char readme_msg[] =
"\t .sym-offset display an address as a symbol and offset\n"
"\t .execname display a common_pid as a program name\n"
"\t .syscall display a syscall id as a syscall name\n\n"
+ "\t .log2 display log2 value rather than raw number\n\n"
"\t The 'pause' parameter can be used to pause an existing hist\n"
"\t trigger or to start a hist trigger but not log any events\n"
"\t until told to do so. 'continue' can be used to start or\n"
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index b040ebefcd64..20a17fdb3fe6 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -68,6 +68,13 @@ static u64 hist_field_pstring(struct hist_field *hist_field, void *event)
return (u64)(unsigned long)*addr;
}
+static u64 hist_field_log2(struct hist_field *hist_field, void *event)
+{
+ u64 val = *(u64 *)(event + hist_field->field->offset);
+
+ return (u64) ilog2(roundup_pow_of_two(val));
+}
+
#define DEFINE_HIST_FIELD_FN(type) \
static u64 hist_field_##type(struct hist_field *hist_field, void *event)\
{ \
@@ -103,6 +110,7 @@ enum hist_field_flags {
HIST_FIELD_EXECNAME = 64,
HIST_FIELD_SYSCALL = 128,
HIST_FIELD_STACKTRACE = 256,
+ HIST_FIELD_LOG2 = 512,
};
struct hist_trigger_attrs {
@@ -349,6 +357,11 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
goto out;
}
+ if (flags & HIST_FIELD_LOG2) {
+ hist_field->fn = hist_field_log2;
+ goto out;
+ }
+
if (is_string_field(field)) {
flags |= HIST_FIELD_STRING;
@@ -500,6 +513,8 @@ 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, "log2"))
+ flags |= HIST_FIELD_LOG2;
else {
ret = -EINVAL;
goto out;
@@ -942,6 +957,9 @@ hist_trigger_entry_print(struct seq_file *m,
key + key_field->offset,
HIST_STACKTRACE_DEPTH);
multiline = true;
+ } else if (key_field->flags & HIST_FIELD_LOG2) {
+ seq_printf(m, "%s: ~ 2^%-2llu", key_field->field->name,
+ *(u64 *)(key + key_field->offset));
} else if (key_field->flags & HIST_FIELD_STRING) {
seq_printf(m, "%s: %-50s", key_field->field->name,
(char *)(key + key_field->offset));
--
2.6.2
--
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