@@ -90,6 +90,8 @@ MODULE_PARM_DESC(verbose, " dynamic_debug/control processing "
static DEFINE_MTREE(mt_funcs);
static DEFINE_MTREE(mt_files);
static DEFINE_MTREE(mt_mods);
+/* cache of composed prefixes for enabled pr_debugs */
+static DEFINE_MTREE(pr_prefixes);
static void dd_mt_scan(struct maple_tree *mt, const char *kind);
static int param_set_do_scan(const char *instr, const struct kernel_param *kp)
@@ -112,6 +114,11 @@ static const struct kernel_param_ops param_ops_do_scan = {
};
module_param_cb(do_scan, ¶m_ops_do_scan, NULL, 0600);
+void ddebug_clear_prefix_cache(const struct _ddebug *dp)
+{
+ mtree_erase(&pr_prefixes, (unsigned long)dp);
+}
+
/* Return the path relative to source root */
static inline const char *trim_prefix(const char *path)
{
@@ -350,6 +357,7 @@ static int ddebug_change(const struct ddebug_query *query,
newflags = (dp->flags & modifiers->mask) | modifiers->flags;
if (newflags == dp->flags)
continue;
+ ddebug_clear_prefix_cache(dp);
#ifdef CONFIG_JUMP_LABEL
if (dp->flags & _DPRINTK_FLAGS_PRINT) {
if (!(newflags & _DPRINTK_FLAGS_PRINT))
@@ -855,8 +863,18 @@ static int remaining(int wrote)
return 0;
}
-static int __dynamic_emit_prefix(const struct _ddebug *desc, char *buf, int pos)
+static int __dynamic_emit_prefix(struct _ddebug *desc, char *buf, int pos)
{
+ char *prefix, *cpy;
+
+ if (desc->flags & _DPRINTK_FLAGS_PREFIX_CACHED) {
+ prefix = (char*) mtree_load(&pr_prefixes, (unsigned long)desc);
+ if (prefix) {
+ pos += snprintf(buf + pos, remaining(pos), "%s", prefix);
+ v4pr_info("using prefix cache:%px %s", buf, buf + pos);
+ return pos;
+ }
+ }
if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME)
pos += snprintf(buf + pos, remaining(pos), "%s:",
desc_modname(desc));
@@ -866,6 +884,13 @@ static int __dynamic_emit_prefix(const struct _ddebug *desc, char *buf, int pos)
if (desc->flags & _DPRINTK_FLAGS_INCL_SOURCENAME)
pos += snprintf(buf + pos, remaining(pos), "%s:",
trim_prefix(desc_filename(desc)));
+
+ /* save dup of buf to cache */
+ cpy = kstrdup(buf + pos, GFP_KERNEL);
+ mtree_store(&pr_prefixes, (unsigned long)desc, (void*)cpy, GFP_KERNEL);
+ desc->flags |= _DPRINTK_FLAGS_PREFIX_CACHED;
+ v3pr_info("filling prefix cache:%px %s", desc, cpy);
+
return pos;
}
Add a private maple-tree to cache any prefix strings required (and then generated) for any enabled pr_debug callsites. And delete any cache entries if any flags are changed afterwards. This cache is strictly per-callsite, so if a function has 20 pr_debugs, all enabled with the same flags: echo function foo +pmfs > /proc/dynamic_debug/control there will be 20 separate, identical cache items created. Maybe this can be trivially improved later. Or lineno could be folded in too, so the %d is rendered once. NB: +tl flags are added outside the cache; the thread-id doesnt belong in the cache, the lineno could be added, esp if the 20:1 sharing isnt trivial enough. NBB: lineno:18 is enormously "sparse". At this point its not so far to pack it into something else. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> --- lib/dynamic_debug.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)