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tracing: Add per-element variable support to tracing_map

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In order to allow information to be passed between trace events, add
support for per-element variables to tracing_map.  This provides a
means for histograms to associate a value or values with an entry when
it's saved or updated, and retrieved by a subsequent event occurrences.

Variables can be set using tracing_map_set_var() and read using
tracing_map_read_var().  tracing_map_var_set() returns true or false
depending on whether or not the variable has been set or not, which is
important for event-matching applications.

tracing_map_read_var_once() reads the variable and resets it to the
'unset' state, implementing read-once variables, which are also
important for event-matching uses.

Link: http://lkml.kernel.org/r/7fa001108252556f0c6dd9d63145eabfe3370d1a.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Tom Zanussi
2018-01-15 20:51:46 -06:00
committed by Steven Rostedt (VMware)
parent ad42febe51
commit 2734b62952
2 changed files with 119 additions and 0 deletions
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11
kernel/trace/tracing_map.h
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@@ -10,6 +10,7 @@
#define TRACING_MAP_VALS_MAX 3
#define TRACING_MAP_FIELDS_MAX (TRACING_MAP_KEYS_MAX + \
TRACING_MAP_VALS_MAX)
#define TRACING_MAP_VARS_MAX 16
#define TRACING_MAP_SORT_KEYS_MAX 2
typedef int (*tracing_map_cmp_fn_t) (void *val_a, void *val_b);
@@ -137,6 +138,8 @@ struct tracing_map_field {
struct tracing_map_elt {
struct tracing_map *map;
struct tracing_map_field *fields;
atomic64_t *vars;
bool *var_set;
void *key;
void *private_data;
};
@@ -192,6 +195,7 @@ struct tracing_map {
int key_idx[TRACING_MAP_KEYS_MAX];
unsigned int n_keys;
struct tracing_map_sort_key sort_key;
unsigned int n_vars;
atomic64_t hits;
atomic64_t drops;
};
@@ -241,6 +245,7 @@ tracing_map_create(unsigned int map_bits,
extern int tracing_map_init(struct tracing_map *map);
extern int tracing_map_add_sum_field(struct tracing_map *map);
extern int tracing_map_add_var(struct tracing_map *map);
extern int tracing_map_add_key_field(struct tracing_map *map,
unsigned int offset,
tracing_map_cmp_fn_t cmp_fn);
@@ -260,7 +265,13 @@ extern int tracing_map_cmp_none(void *val_a, void *val_b);
extern void tracing_map_update_sum(struct tracing_map_elt *elt,
unsigned int i, u64 n);
extern void tracing_map_set_var(struct tracing_map_elt *elt,
unsigned int i, u64 n);
extern bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i);
extern u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i);
extern u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i);
extern u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i);
extern void tracing_map_set_field_descr(struct tracing_map *map,
unsigned int i,
unsigned int key_offset,