From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Namhyung Kim <namhyung@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Tom Zanussi <tom.zanussi@linux.intel.com>
Subject: [for-next][PATCH 18/24] tracing: Add hist trigger comments for variable-related fields
Date: Fri, 21 Dec 2018 12:56:36 -0500 [thread overview]
Message-ID: <20181221175658.347685840@goodmis.org> (raw)
In-Reply-To: 20181221175618.968519903@goodmis.org
From: Tom Zanussi <tom.zanussi@linux.intel.com>
Add a few comments to help clarify how variable and variable reference
fields are used in the code.
Link: http://lkml.kernel.org/r/ea857ce948531d7bec712bbb0f38360aa1d378ec.1545161087.git.tom.zanussi@linux.intel.com
Acked-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_events_hist.c | 36 ++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1b1aee944588..c5448c103770 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -40,6 +40,16 @@ enum field_op_id {
FIELD_OP_UNARY_MINUS,
};
+/*
+ * A hist_var (histogram variable) contains variable information for
+ * hist_fields having the HIST_FIELD_FL_VAR or HIST_FIELD_FL_VAR_REF
+ * flag set. A hist_var has a variable name e.g. ts0, and is
+ * associated with a given histogram trigger, as specified by
+ * hist_data. The hist_var idx is the unique index assigned to the
+ * variable by the hist trigger's tracing_map. The idx is what is
+ * used to set a variable's value and, by a variable reference, to
+ * retrieve it.
+ */
struct hist_var {
char *name;
struct hist_trigger_data *hist_data;
@@ -56,11 +66,29 @@ struct hist_field {
const char *type;
struct hist_field *operands[HIST_FIELD_OPERANDS_MAX];
struct hist_trigger_data *hist_data;
+
+ /*
+ * Variable fields contain variable-specific info in var.
+ */
struct hist_var var;
enum field_op_id operator;
char *system;
char *event_name;
+
+ /*
+ * The name field is used for EXPR and VAR_REF fields. VAR
+ * fields contain the variable name in var.name.
+ */
char *name;
+
+ /*
+ * When a histogram trigger is hit, if it has any references
+ * to variables, the values of those variables are collected
+ * into a var_ref_vals array by resolve_var_refs(). The
+ * current value of each variable is read from the tracing_map
+ * using the hist field's hist_var.idx and entered into the
+ * var_ref_idx entry i.e. var_ref_vals[var_ref_idx].
+ */
unsigned int var_ref_idx;
bool read_once;
};
@@ -365,6 +393,14 @@ struct action_data {
union {
struct {
+ /*
+ * When a histogram trigger is hit, the values of any
+ * references to variables, including variables being passed
+ * as parameters to synthetic events, are collected into a
+ * var_ref_vals array. This var_ref_idx is the index of the
+ * first param in the array to be passed to the synthetic
+ * event invocation.
+ */
unsigned int var_ref_idx;
char *match_event;
char *match_event_system;
--
2.19.2
next prev parent reply other threads:[~2018-12-21 17:58 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-21 17:56 [for-next][PATCH 00/24] tracing: Updates for the next (coming soon) merge window Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 01/24] ftrace: Allow ftrace_replace_code() to be schedulable Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 02/24] arm64: ftrace: Set FTRACE_MAY_SLEEP before ftrace_modify_all_code() Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 03/24] fgraph: Add comment to describe ftrace_graph_get_ret_stack Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 04/24] x86/ftrace: Do not call function graph from dynamic trampolines Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 05/24] powerpc/frace: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack Steven Rostedt
2018-12-22 9:51 ` Michael Ellerman
2018-12-22 12:24 ` Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 06/24] sparc64: " Steven Rostedt
2018-12-21 18:24 ` David Miller
2018-12-21 19:29 ` Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 07/24] sh: ftrace: " Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 08/24] arm64: " Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 10/24] seq_buf: Use size_t for len in seq_buf_puts() Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 11/24] tracing: Fix ftrace_graph_get_ret_stack() to use task and not current Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 12/24] tracing: Remove unnecessary hist trigger struct field Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 13/24] tracing: Change strlen to sizeof for hist trigger static strings Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 14/24] tracing: Use var_refs[] for hist trigger reference checking Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 15/24] tracing: Remove open-coding of hist trigger var_ref management Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 16/24] tracing: Use hist triggers var_ref array to destroy var_refs Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 17/24] tracing: Remove hist trigger synth_var_refs Steven Rostedt
2018-12-21 17:56 ` Steven Rostedt [this message]
2018-12-21 17:56 ` [for-next][PATCH 19/24] tracing: Merge seq_print_sym_short() and seq_print_sym_offset() Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 21/24] tracing: Simplify printfing in seq_print_sym Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 23/24] string.h: Add strncmp_prefix() helper macro Steven Rostedt
2018-12-21 18:51 ` Linus Torvalds
2018-12-21 19:40 ` Steven Rostedt
2018-12-21 20:01 ` Linus Torvalds
2018-12-21 20:35 ` Steven Rostedt
2018-12-21 20:46 ` Joe Perches
2018-12-21 20:54 ` Steven Rostedt
2018-12-21 20:58 ` Andreas Schwab
2018-12-21 21:08 ` Steven Rostedt
2018-12-21 22:20 ` Joe Perches
2018-12-21 22:29 ` Linus Torvalds
2018-12-21 22:58 ` Steven Rostedt
2018-12-21 22:55 ` Steven Rostedt
2018-12-23 22:01 ` Rasmus Villemoes
2018-12-23 22:56 ` Steven Rostedt
2018-12-23 23:52 ` Rasmus Villemoes
2018-12-24 0:05 ` Steven Rostedt
2018-12-23 23:01 ` Joe Perches
2018-12-21 20:58 ` Steven Rostedt
[not found] ` <CAHk-=wjtkvFUuRNZU67KccuUKYHw=pYoDMQJ_9OVDFxOwmK9zQ@mail.gmail.com>
2018-12-21 20:55 ` Steven Rostedt
2018-12-21 22:08 ` Linus Torvalds
2018-12-21 22:48 ` Steven Rostedt
2018-12-21 22:57 ` Linus Torvalds
2018-12-21 23:03 ` Steven Rostedt
2018-12-22 10:20 ` Malcolm Priestley
2018-12-22 12:26 ` Steven Rostedt
2018-12-21 17:56 ` [for-next][PATCH 24/24] tracing: Use strncmp_prefix() helper for histogram code Steven Rostedt
[not found] ` <20181221175656.827708767@goodmis.org>
2018-12-21 18:00 ` [for-next][PATCH 09/24] seq_buf: Make seq_buf_puts() null-terminate the buffer Steven Rostedt
2018-12-21 18:05 ` Steven Rostedt
2018-12-27 5:25 ` Michael Ellerman
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