It is useful to see how many times each function is called, particularly in the context of its callers. A flamegraph is a way of showing this.
Support output in this format which can be used by the flamegraph.pl script, to generate an SVG image for browsing.
Signed-off-by: Simon Glass sjg@chromium.org ---
tools/proftool.c | 272 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 271 insertions(+), 1 deletion(-)
diff --git a/tools/proftool.c b/tools/proftool.c index 588ae48a0c8..844ff3d0d06 100644 --- a/tools/proftool.c +++ b/tools/proftool.c @@ -6,7 +6,7 @@
/* * Decode and dump U-Boot trace information into formats that can be used - * by trace-cmd or kernelshark + * by trace-cmd, kernelshark or flamegraph.pl * * See doc/develop/trace.rst for more information */ @@ -27,6 +27,8 @@ #include <trace.h> #include <abuf.h>
+#include <linux/list.h> + /* Set to 1 to emit version 7 file (currently this doesn't work) */ #define VERSION7 0
@@ -37,6 +39,18 @@ #define __ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask)) #define ALIGN(x, a) __ALIGN_MASK((x), (typeof(x))(a) - 1)
+/** + * container_of - cast a member of a structure out to the containing structure + * @ptr: the pointer to the member. + * @type: the type of the container struct this is embedded in. + * @member: the name of the member within the struct. + * + * (this is needed by list.h) + */ +#define container_of(ptr, type, member) ({ \ + const typeof( ((type *)0)->member ) *__mptr = (ptr); \ + (type *)( (char *)__mptr - offsetof(type,member) );}) + enum { FUNCF_TRACE = 1 << 0, /* Include this function in trace */ TRACE_PAGE_SIZE = 4096, /* Assumed page size for trace */ @@ -101,6 +115,38 @@ enum trace_type { TRACE_GRAPH_ENT, };
+/** + * struct flame_node - a node in the call-stack tree + * + * Each stack frame detected in the trace is given a node corresponding to a + * function call in the call stack. Functions can appear multiple times when + * they are called by a different set of parent functions. + * + * @parent: Parent node (the call stack for the function that called this one) + * @child_head: List of children of this node (functions called from here) + * @sibling: Next node in the list of children + * @func: Function this node refers to (NULL for root node) + * @count: Number of times this call-stack occurred + */ +struct flame_node { + struct flame_node *parent; + struct list_head child_head; + struct list_head sibling_node; + struct func_info *func; + int count; +}; + +/** + * struct flame_state - state information for building the flame graph + * + * @node: Current node being processed (corresponds to a function call) + * @nodes: Number of nodes created (running count) + */ +struct flame_state { + struct flame_node *node; + int nodes; +}; + /** * struct func_info - information recorded for each function * @@ -221,6 +267,7 @@ static void usage(void) "\n" "Commands\n" " dump-ftrace\t\tDump out records in ftrace format for use by trace-cmd\n" + " dump-flamegraph\tWrite a file for use with flamegraph.pl\n" "\n" "Options:\n" " -c <cfg>\tSpecify config file\n" @@ -1517,6 +1564,218 @@ static int make_ftrace(FILE *fout, enum out_format_t out_format) return 0; }
+/** + * create_node() - Create a new node in the flamegraph tree + * + * @msg: Message to use for debugging if something goes wrong + * Returns: Pointer to newly created node, or NULL on error + */ +static struct flame_node *create_node(const char *msg) +{ + struct flame_node *node; + + node = calloc(1, sizeof(*node)); + if (!node) { + fprintf(stderr, "Out of memory for %s\n", msg); + return NULL; + } + INIT_LIST_HEAD(&node->child_head); + + return node; +} + +/** + * process_call(): Add a call to the flamegraph info + * + * For function calls, if this call stack has been seen before, this increments + * the call count, creating a new node if needed. + * + * For function returns, it adds up the time spent in this call stack, + * subtracting the time spent by child functions. + * + * @state: Current flamegraph state + * @entry: true if this is a function entry, false if a function exit + * @timestamp: Timestamp from the trace file (in microseconds) + * @func: Function that was called/returned from + * + * Returns: 0 on success, -ve on error + */ +static int process_call(struct flame_state *state, bool entry, ulong timestamp, + struct func_info *func) +{ + struct flame_node *node = state->node; + + if (entry) { + struct flame_node *child, *chd; + + /* see if we have this as a child node already */ + child = NULL; + list_for_each_entry(chd, &node->child_head, sibling_node) { + if (chd->func == func) { + child = chd; + break; + } + } + if (!child) { + /* create a new node */ + child = create_node("child"); + if (!child) + return -1; + list_add_tail(&child->sibling_node, &node->child_head); + child->func = func; + child->parent = node; + state->nodes++; + } + debug("entry %s: move from %s to %s\n", func->name, + node->func ? node->func->name : "(root)", + child->func->name); + child->count++; + node = child; + } else if (node->parent) { + debug("exit %s: move from %s to %s\n", func->name, + node->func->name, node->parent->func ? + node->parent->func->name : "(root)"); + node = node->parent; + } + + state->node = node; + + return 0; +} + +/** + * make_flame_tree() - Create a tree of stack traces + * + * Set up a tree, with the root node having the top-level functions as children + * and the leaf nodes being leaf functions. Each node has a count of how many + * times this function appears in the trace + * + * @treep: Returns the resulting flamegraph tree + * Returns: 0 on success, -ve on error + */ +static int make_flame_tree(struct flame_node **treep) +{ + struct flame_state state; + struct flame_node *tree; + struct trace_call *call; + int missing_count = 0; + int i, depth; + + /* + * The first thing in the trace may not be the top-level function, so + * set the initial depth so that no function goes below depth 0 + */ + depth = -calc_min_depth(); + + tree = create_node("tree"); + if (!tree) + return -1; + state.node = tree; + state.nodes = 0; + + for (i = 0, call = call_list; i < call_count; i++, call++) { + bool entry = TRACE_CALL_TYPE(call) == FUNCF_ENTRY; + ulong timestamp = call->flags & FUNCF_TIMESTAMP_MASK; + struct func_info *func; + + if (entry) + depth++; + else + depth--; + + func = find_func_by_offset(call->func); + if (!func) { + warn("Cannot find function at %lx\n", + text_offset + call->func); + missing_count++; + continue; + } + + if (process_call(&state, entry, timestamp, func)) + return -1; + } + fprintf(stderr, "%d nodes\n", state.nodes); + *treep = tree; + + return 0; +} + +/** + * output_tree() - Output a flamegraph tree + * + * Writes the tree out to a file in a format suitable for flamegraph.pl + * + * This works by maintaining a string shared across all recursive calls. The + * function name for this node is added to the existing string, to make up the + * full call-stack description. For example, on entry, @str might contain: + * + * "initf_bootstage;bootstage_mark_name" + * ^ @base + * + * with @base pointing to the \0 at the end of the string. This function adds + * a ';' following by the name of the current function, e.g. "timer_get_boot_us" + * as well as the output value, to get the full line: + * + * initf_bootstage;bootstage_mark_name;timer_get_boot_us 123 + * + * @fout: Output file + * @node: Node to output (pass the whole tree at first) + * @str: String to use to build the output line (e.g. 500 charas long) + * @maxlen: Maximum length of string + * @base: Current base position in the string + * @treep: Returns the resulting flamegraph tree + * Returns 0 if OK, -1 on error + */ +static int output_tree(FILE *fout, const struct flame_node *node, + char *str, int maxlen, int base) +{ + const struct flame_node *child; + int pos; + + if (node->count) + fprintf(fout, "%s %d\n", str, node->count); + + pos = base; + if (pos) + str[pos++] = ';'; + list_for_each_entry(child, &node->child_head, sibling_node) { + int len; + + len = strlen(child->func->name); + if (pos + len + 1 >= maxlen) { + fprintf(stderr, "String too short (%d chars)\n", + maxlen); + return -1; + } + strcpy(str + pos, child->func->name); + if (output_tree(fout, child, str, maxlen, pos + len)) + return -1; + } + + return 0; +} + +/** + * make_flamegraph() - Write out a flame graph + * + * @fout: Output file + * Returns 0 if OK, -1 on error + */ +static int make_flamegraph(FILE *fout) +{ + struct flame_node *tree; + char str[500]; + + if (make_flame_tree(&tree)) + return -1; + + *str = '\0'; + if (output_tree(fout, tree, str, sizeof(str), 0)) + return -1; + + return 0; +} + /** * prof_tool() - Performs requested action * @@ -1560,6 +1819,17 @@ static int prof_tool(int argc, char *const argv[], } err = make_ftrace(fout, out_format); fclose(fout); + } else if (!strcmp(cmd, "dump-flamegraph")) { + FILE *fout; + + fout = fopen(out_fname, "w"); + if (!fout) { + fprintf(stderr, "Cannot write file '%s'\n", + out_fname); + return -1; + } + err = make_flamegraph(fout); + fclose(fout); } else { warn("Unknown command '%s'\n", cmd); }