[PATCH 2/7] perf machine: Use cached rbtrees

From: Davidlohr Bueso
Date: Sun Nov 26 2017 - 21:35:31 EST

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At the cost of an extra pointer, we can avoid the O(logN) cost
of finding the first element in the tree (smallest node), which
is something required for nearly every operation dealing with
machine->guests and threads->entries.

The conversion is straightforward, however, it's worth noticing
that the rb_erase_init() calls have been replaced by rb_erase_cached()
which has no _init() flavor, however, the node is explicitly
cleared next anyway, which was redundant until now.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
---
tools/perf/util/build-id.c | 12 +++++++----
tools/perf/util/machine.c | 52 ++++++++++++++++++++++++++--------------------
tools/perf/util/machine.h | 4 ++--
3 files changed, 40 insertions(+), 28 deletions(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 7f8553630c4d..1aa96bb85189 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -367,7 +367,8 @@ int perf_session__write_buildid_table(struct perf_session *session,
if (err)
return err;

- for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&session->machines.guests);
+ nd; nd = rb_next(nd)) {
struct machine *pos = rb_entry(nd, struct machine, rb_node);
err = machine__write_buildid_table(pos, fd);
if (err)
@@ -400,7 +401,8 @@ int dsos__hit_all(struct perf_session *session)
if (err)
return err;

- for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&session->machines.guests);
+ nd; nd = rb_next(nd)) {
struct machine *pos = rb_entry(nd, struct machine, rb_node);

err = machine__hit_all_dsos(pos);
@@ -855,7 +857,8 @@ int perf_session__cache_build_ids(struct perf_session *session)

ret = machine__cache_build_ids(&session->machines.host);

- for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&session->machines.guests);
+ nd; nd = rb_next(nd)) {
struct machine *pos = rb_entry(nd, struct machine, rb_node);
ret |= machine__cache_build_ids(pos);
}
@@ -872,7 +875,8 @@ bool perf_session__read_build_ids(struct perf_session *session, bool with_hits)
struct rb_node *nd;
bool ret = machine__read_build_ids(&session->machines.host, with_hits);

- for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&session->machines.guests);
+ nd; nd = rb_next(nd)) {
struct machine *pos = rb_entry(nd, struct machine, rb_node);
ret |= machine__read_build_ids(pos, with_hits);
}
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 64d255f6a537..a47e87f8664c 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -40,7 +40,7 @@ static void machine__threads_init(struct machine *machine)

for (i = 0; i < THREADS__TABLE_SIZE; i++) {
struct threads *threads = &machine->threads[i];
- threads->entries = RB_ROOT;
+ threads->entries = RB_ROOT_CACHED;
init_rwsem(&threads->lock);
threads->nr = 0;
INIT_LIST_HEAD(&threads->dead);
@@ -157,7 +157,7 @@ void machine__delete_threads(struct machine *machine)
for (i = 0; i < THREADS__TABLE_SIZE; i++) {
struct threads *threads = &machine->threads[i];
down_write(&threads->lock);
- nd = rb_first(&threads->entries);
+ nd = rb_first_cached(&threads->entries);
while (nd) {
struct thread *t = rb_entry(nd, struct thread, rb_node);

@@ -199,7 +199,7 @@ void machine__delete(struct machine *machine)
void machines__init(struct machines *machines)
{
machine__init(&machines->host, "", HOST_KERNEL_ID);
- machines->guests = RB_ROOT;
+ machines->guests = RB_ROOT_CACHED;
}

void machines__exit(struct machines *machines)
@@ -211,9 +211,10 @@ void machines__exit(struct machines *machines)
struct machine *machines__add(struct machines *machines, pid_t pid,
const char *root_dir)
{
- struct rb_node **p = &machines->guests.rb_node;
+ struct rb_node **p = &machines->guests.rb_root.rb_node;
struct rb_node *parent = NULL;
struct machine *pos, *machine = malloc(sizeof(*machine));
+ bool leftmost = true;

if (machine == NULL)
return NULL;
@@ -228,12 +229,14 @@ struct machine *machines__add(struct machines *machines, pid_t pid,
pos = rb_entry(parent, struct machine, rb_node);
if (pid < pos->pid)
p = &(*p)->rb_left;
- else
+ else {
p = &(*p)->rb_right;
+ leftmost = false;
+ }
}

rb_link_node(&machine->rb_node, parent, p);
- rb_insert_color(&machine->rb_node, &machines->guests);
+ rb_insert_color_cached(&machine->rb_node, &machines->guests, leftmost);

return machine;
}
@@ -244,7 +247,7 @@ void machines__set_comm_exec(struct machines *machines, bool comm_exec)

machines->host.comm_exec = comm_exec;

- for (nd = rb_first(&machines->guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
struct machine *machine = rb_entry(nd, struct machine, rb_node);

machine->comm_exec = comm_exec;
@@ -253,7 +256,7 @@ void machines__set_comm_exec(struct machines *machines, bool comm_exec)

struct machine *machines__find(struct machines *machines, pid_t pid)
{
- struct rb_node **p = &machines->guests.rb_node;
+ struct rb_node **p = &machines->guests.rb_root.rb_node;
struct rb_node *parent = NULL;
struct machine *machine;
struct machine *default_machine = NULL;
@@ -316,7 +319,7 @@ void machines__process_guests(struct machines *machines,
{
struct rb_node *nd;

- for (nd = rb_first(&machines->guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
struct machine *pos = rb_entry(nd, struct machine, rb_node);
process(pos, data);
}
@@ -343,7 +346,8 @@ void machines__set_id_hdr_size(struct machines *machines, u16 id_hdr_size)

machines->host.id_hdr_size = id_hdr_size;

- for (node = rb_first(&machines->guests); node; node = rb_next(node)) {
+ for (node = rb_first_cached(&machines->guests);
+ node; node = rb_next(node)) {
machine = rb_entry(node, struct machine, rb_node);
machine->id_hdr_size = id_hdr_size;
}
@@ -407,9 +411,10 @@ static struct thread *____machine__findnew_thread(struct machine *machine,
pid_t pid, pid_t tid,
bool create)
{
- struct rb_node **p = &threads->entries.rb_node;
+ struct rb_node **p = &threads->entries.rb_root.rb_node;
struct rb_node *parent = NULL;
struct thread *th;
+ bool leftmost = true;

/*
* Front-end cache - TID lookups come in blocks,
@@ -438,8 +443,10 @@ static struct thread *____machine__findnew_thread(struct machine *machine,

if (tid < th->tid)
p = &(*p)->rb_left;
- else
+ else {
p = &(*p)->rb_right;
+ leftmost = false;
+ }
}

if (!create)
@@ -448,7 +455,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine,
th = thread__new(pid, tid);
if (th != NULL) {
rb_link_node(&th->rb_node, parent, p);
- rb_insert_color(&th->rb_node, &threads->entries);
+ rb_insert_color_cached(&th->rb_node, &threads->entries, leftmost);

/*
* We have to initialize map_groups separately
@@ -459,7 +466,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine,
* leader and that would screwed the rb tree.
*/
if (thread__init_map_groups(th, machine)) {
- rb_erase_init(&th->rb_node, &threads->entries);
+ rb_erase_cached(&th->rb_node, &threads->entries);
RB_CLEAR_NODE(&th->rb_node);
thread__put(th);
return NULL;
@@ -698,7 +705,7 @@ size_t machines__fprintf_dsos(struct machines *machines, FILE *fp)
struct rb_node *nd;
size_t ret = __dsos__fprintf(&machines->host.dsos.head, fp);

- for (nd = rb_first(&machines->guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
struct machine *pos = rb_entry(nd, struct machine, rb_node);
ret += __dsos__fprintf(&pos->dsos.head, fp);
}
@@ -718,7 +725,7 @@ size_t machines__fprintf_dsos_buildid(struct machines *machines, FILE *fp,
struct rb_node *nd;
size_t ret = machine__fprintf_dsos_buildid(&machines->host, fp, skip, parm);

- for (nd = rb_first(&machines->guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
struct machine *pos = rb_entry(nd, struct machine, rb_node);
ret += machine__fprintf_dsos_buildid(pos, fp, skip, parm);
}
@@ -758,7 +765,7 @@ size_t machine__fprintf(struct machine *machine, FILE *fp)

ret = fprintf(fp, "Threads: %u\n", threads->nr);

- for (nd = rb_first(&threads->entries); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&threads->entries); nd; nd = rb_next(nd)) {
struct thread *pos = rb_entry(nd, struct thread, rb_node);

ret += thread__fprintf(pos, fp);
@@ -964,7 +971,7 @@ int machines__create_guest_kernel_maps(struct machines *machines)

void machines__destroy_kernel_maps(struct machines *machines)
{
- struct rb_node *next = rb_first(&machines->guests);
+ struct rb_node *next = rb_first_cached(&machines->guests);

machine__destroy_kernel_maps(&machines->host);

@@ -972,7 +979,7 @@ void machines__destroy_kernel_maps(struct machines *machines)
struct machine *pos = rb_entry(next, struct machine, rb_node);

next = rb_next(&pos->rb_node);
- rb_erase(&pos->rb_node, &machines->guests);
+ rb_erase_cached(&pos->rb_node, &machines->guests);
machine__delete(pos);
}
}
@@ -1519,7 +1526,7 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
BUG_ON(refcount_read(&th->refcnt) == 0);
if (lock)
down_write(&threads->lock);
- rb_erase_init(&th->rb_node, &threads->entries);
+ rb_erase_cached(&th->rb_node, &threads->entries);
RB_CLEAR_NODE(&th->rb_node);
--threads->nr;
/*
@@ -2243,7 +2250,8 @@ int machine__for_each_thread(struct machine *machine,

for (i = 0; i < THREADS__TABLE_SIZE; i++) {
threads = &machine->threads[i];
- for (nd = rb_first(&threads->entries); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&threads->entries);
+ nd; nd = rb_next(nd)) {
thread = rb_entry(nd, struct thread, rb_node);
rc = fn(thread, priv);
if (rc != 0)
@@ -2270,7 +2278,7 @@ int machines__for_each_thread(struct machines *machines,
if (rc != 0)
return rc;

- for (nd = rb_first(&machines->guests); nd; nd = rb_next(nd)) {
+ for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
struct machine *machine = rb_entry(nd, struct machine, rb_node);

rc = machine__for_each_thread(machine, fn, priv);
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index 5ce860b64c74..864cffa8e06b 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -29,7 +29,7 @@ struct vdso_info;
#define THREADS__TABLE_SIZE (1 << THREADS__TABLE_BITS)

struct threads {
- struct rb_root entries;
+ struct rb_root_cached entries;
struct rw_semaphore lock;
unsigned int nr;
struct list_head dead;
@@ -126,7 +126,7 @@ typedef void (*machine__process_t)(struct machine *machine, void *data);

struct machines {
struct machine host;
- struct rb_root guests;
+ struct rb_root_cached guests;
};

void machines__init(struct machines *machines);
--
2.13.6

Next message: Minchan Kim: "Re: [PATCH] mm/vmscan: make do_shrink_slab more robust."
Previous message: Davidlohr Bueso: "[PATCH 5/7] perf symbols: Use cached rbtrees"
In reply to: Davidlohr Bueso: "[PATCH 5/7] perf symbols: Use cached rbtrees"
Next in thread: Andi Kleen: "Re: [PATCH -tip 0/7] tools/perf: Update rbtree implementation and optimize users"
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