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Message-ID: <20140918151057.GG2770@kernel.org>
Date: Thu, 18 Sep 2014 12:10:57 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Waiman Long <Waiman.Long@...com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Paul Mackerras <paulus@...ba.org>,
Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
Scott J Norton <scott.norton@...com>,
Douglas Hatch <doug.hatch@...com>,
Don Zickus <dzickus@...hat.com>, Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH v3 1/2] perf tool: improves DSO long names search speed
with RB tree
Em Thu, Sep 18, 2014 at 09:30:20AM -0400, Waiman Long escreveu:
> +++ b/tools/perf/util/dso.c
> @@ -651,6 +651,80 @@ struct dso *dso__kernel_findnew(struct machine *machine, const char *name,
> return dso;
> +/*
> + * RB root of DSOs sorted by the long name
> + */
> +struct rb_root dso__root = { NULL };
Why do we still have a global variable for this? I thought that we would
be having this in struct machine?
Ok, I shouldn't have done this, but I went on and looked at the second
patch, and there, this goes away, why not avoid introducing the global
in the first place?
I.e. the existing code operates on a data structure that holds struct
dsos, you are switching to a new data structure, so it looked natural to
me to do this in one step, no?
Also at some point I thought about adding rb_tree helper functions to do
some rb__for_each() like operation, i.e. to sequentially access the
rb_tree instead of using it for searching using its key. PeterZ
rightfully nacked that because that would, IIRC, encourage people to use
a rb_tree to do linear searches for normal operation, i.e. not just for
rb_tree__printf() dump like routines:
https://lkml.org/lkml/2010/1/13/227
Also I saw at least one place where some foo__for_each_entry_safe() is
used but the loop doesn't look like it will remove/add anything to the
data structure that is being made "_safe", i.e. it should remain
foo__for_each_entry(), as it was before.
So, I would _keep_ the list_head, or else replace it with a another
rb_node to do lookups on it by shortname the same way we do for long
names.
The cheapest thing now would be for solving your problem, i.e. use a
rb_tree for searching for long names, keep the list_head for short names
linear searches.
I suggest having a
struct dsos {
struct list_head short_names;
struct rb_root long_names;
};
Then make struct machine use this type for:
struct dsos kernel_dsos, user_dsos;
Then all those dsos__find* routines stop receiving a list_head pointer
and start receiving a "struct dsos" instance.
That way it can add the dso to both containers, the one "sorted" by
short names (that linear search, just like before) and to the rb_tree
sorted by long names.
- Arnaldo
> +/*
> + * Find a matching entry and/or link current entry to RB tree.
> + * Either one of the dso or name parameter must be non-NULL or the
> + * function will not work.
> + */
> +static struct dso *dso__findlink_by_longname(struct rb_root *root,
> + struct dso *dso, const char *name)
> +{
> + struct rb_node **p = &root->rb_node;
> + struct rb_node *parent = NULL;
> + int warned = false;
> +
> + if (!name)
> + name = dso->long_name;
> + /*
> + * Find node with the matching name
> + */
> + while (*p) {
> + struct dso *this = rb_entry(*p, struct dso, rb_node);
> + long rc = (long)strcmp(name, this->long_name);
> +
> + parent = *p;
> + if (rc == 0) {
> + /*
> + * In case the new DSO is a duplicate of an existing
> + * one, print an one-time warning & sort the entry
> + * by its DSO address.
> + */
> + if (!dso || (dso == this))
> + return this; /* Find matching dso */
> + /*
> + * The kernel DSOs may have duplicated long name,
> + * so don't print warning for them.
> + */
> + if (!warned && !strstr(name, "kernel.kallsyms")
> + && !strstr(name, "/vmlinux")) {
> + pr_warning("Duplicated dso long name: %s\n",
> + name);
> + warned = true;
> + }
> + rc = (long)dso - (long)this;
> + }
> + if (rc < 0)
> + p = &parent->rb_left;
> + else
> + p = &parent->rb_right;
> + }
> + if (dso) {
> + /* Add new node and rebalance tree */
> + rb_link_node(&dso->rb_node, parent, p);
> + rb_insert_color(&dso->rb_node, root);
> + }
> + return NULL;
> +}
> +
> +static inline struct dso *
> +dso__find_by_longname(struct rb_root *root, const char *name)
> +{
> + return dso__findlink_by_longname(root, NULL, name);
> +}
> +
> +/*
> + * Unlink the longname-sorted RB tree node
> + */
> +static inline void dso__rb_unlink(struct rb_root *root, struct dso *dso)
> +{
> + rb_erase(&dso->rb_node, root);
> +}
> +
> void dso__set_long_name(struct dso *dso, const char *name, bool name_allocated)
> {
> if (name == NULL)
> @@ -753,6 +827,8 @@ struct dso *dso__new(const char *name)
> dso->a2l_fails = 1;
> dso->kernel = DSO_TYPE_USER;
> dso->needs_swap = DSO_SWAP__UNSET;
> + dso->rb_root = NULL;
> + RB_CLEAR_NODE(&dso->rb_node);
> INIT_LIST_HEAD(&dso->node);
> INIT_LIST_HEAD(&dso->data.open_entry);
> }
> @@ -775,6 +851,10 @@ void dso__delete(struct dso *dso)
> zfree((char **)&dso->long_name);
> dso->long_name_allocated = false;
> }
> + if (dso->rb_root) {
> + dso__rb_unlink(dso->rb_root, dso);
> + dso->rb_root = NULL;
> + }
>
> dso__data_close(dso);
> dso_cache__free(&dso->data.cache);
> @@ -852,6 +932,8 @@ bool __dsos__read_build_ids(struct list_head *head, bool with_hits)
> void dsos__add(struct list_head *head, struct dso *dso)
> {
> list_add_tail(&dso->node, head);
> + dso__findlink_by_longname(&dso__root, dso, NULL);
> + dso->rb_root = &dso__root;
> }
>
> struct dso *dsos__find(const struct list_head *head, const char *name, bool cmp_short)
> @@ -864,10 +946,7 @@ struct dso *dsos__find(const struct list_head *head, const char *name, bool cmp_
> return pos;
> return NULL;
> }
> - list_for_each_entry(pos, head, node)
> - if (strcmp(pos->long_name, name) == 0)
> - return pos;
> - return NULL;
> + return dso__find_by_longname(&dso__root, name);
> }
>
> struct dso *__dsos__findnew(struct list_head *head, const char *name)
> diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
> index 5e463c0..75cda1d 100644
> --- a/tools/perf/util/dso.h
> +++ b/tools/perf/util/dso.h
> @@ -92,6 +92,8 @@ struct dso_cache {
>
> struct dso {
> struct list_head node;
> + struct rb_node rb_node; /* rbtree sorted by long name */
> + struct rb_root *rb_root; /* pointer to rbtree root */
> struct rb_root symbols[MAP__NR_TYPES];
> struct rb_root symbol_names[MAP__NR_TYPES];
> void *a2l;
> --
> 1.7.1
--
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