RE: [PATCH RFC V2 05/10] perf tools: lock to protect thread list

[Liang, Kan]

> 
> SNIP
> 
> > +   pthread_mutex_unlock(>namespaces_lock);
> > +
> > return 0;
> >  }
> >
> > -void thread__namespaces_id(const struct thread *thread,
> > +void thread__namespaces_id(struct thread *thread,
> >u64 *dev, u64 *ino)
> >  {
> > struct namespaces *ns;
> >
> > +   pthread_mutex_lock(>namespaces_lock);
> > ns = thread__namespaces(thread);
> 
> isn't it just thread__namespaces that needs this lock?

I also wanted to protect
*dev = ns ? ns->link_info[CGROUP_NS_INDEX].dev : 0;
*ino = ns ? ns->link_info[CGROUP_NS_INDEX].ino : 0;
Because I was not sure if ns is still accurate when we try to use
it later.
But for our case (perf top event synthesizing), it looks I worried too much.
Namespaces event isn't processed at all.  
So yes, we don't need patch 4 for the optimization.

Based on the same reason, I used comm_str in patch 3.
It's not help for the optimization either, but should be useful for future.

Anyway, I think I will drop patch 3 & 4 for V3.

Thanks,
Kan

> 
> if that's the case we don't need the change for __hists__add_entry in
> previous patch
> 
> jirka

RE: [PATCH RFC V2 05/10] perf tools: lock to protect thread list

[Liang, Kan]

> 
> SNIP
> 
> > +   pthread_mutex_unlock(>namespaces_lock);
> > +
> > return 0;
> >  }
> >
> > -void thread__namespaces_id(const struct thread *thread,
> > +void thread__namespaces_id(struct thread *thread,
> >u64 *dev, u64 *ino)
> >  {
> > struct namespaces *ns;
> >
> > +   pthread_mutex_lock(>namespaces_lock);
> > ns = thread__namespaces(thread);
> 
> isn't it just thread__namespaces that needs this lock?

I also wanted to protect
*dev = ns ? ns->link_info[CGROUP_NS_INDEX].dev : 0;
*ino = ns ? ns->link_info[CGROUP_NS_INDEX].ino : 0;
Because I was not sure if ns is still accurate when we try to use
it later.
But for our case (perf top event synthesizing), it looks I worried too much.
Namespaces event isn't processed at all.  
So yes, we don't need patch 4 for the optimization.

Based on the same reason, I used comm_str in patch 3.
It's not help for the optimization either, but should be useful for future.

Anyway, I think I will drop patch 3 & 4 for V3.

Thanks,
Kan

> 
> if that's the case we don't need the change for __hists__add_entry in
> previous patch
> 
> jirka

Re: [PATCH RFC V2 05/10] perf tools: lock to protect thread list

[Jiri Olsa]

On Sun, Sep 10, 2017 at 07:23:18PM -0700, kan.li...@intel.com wrote:

SNIP

> + pthread_mutex_unlock(>namespaces_lock);
> +
>   return 0;
>  }
>  
> -void thread__namespaces_id(const struct thread *thread,
> +void thread__namespaces_id(struct thread *thread,
>  u64 *dev, u64 *ino)
>  {
>   struct namespaces *ns;
>  
> + pthread_mutex_lock(>namespaces_lock);
>   ns = thread__namespaces(thread);

isn't it just thread__namespaces that needs this lock?

if that's the case we don't need the change for __hists__add_entry
in previous patch

jirka

Re: [PATCH RFC V2 05/10] perf tools: lock to protect thread list

[Jiri Olsa]

On Sun, Sep 10, 2017 at 07:23:18PM -0700, kan.li...@intel.com wrote:

SNIP

> + pthread_mutex_unlock(>namespaces_lock);
> +
>   return 0;
>  }
>  
> -void thread__namespaces_id(const struct thread *thread,
> +void thread__namespaces_id(struct thread *thread,
>  u64 *dev, u64 *ino)
>  {
>   struct namespaces *ns;
>  
> + pthread_mutex_lock(>namespaces_lock);
>   ns = thread__namespaces(thread);

isn't it just thread__namespaces that needs this lock?

if that's the case we don't need the change for __hists__add_entry
in previous patch

jirka

[PATCH RFC V2 05/10] perf tools: lock to protect thread list

[kan . liang]

From: Kan Liang 

Add two locks to protect namespaces_list and comm_list.

The comm which is used in db-export are not protected. Because the
multithread code will not touch it. It can be added later if required.

Signed-off-by: Kan Liang 
---
 tools/perf/ui/browsers/hists.c |  2 +-
 tools/perf/util/thread.c   | 60 +-
 tools/perf/util/thread.h   |  6 +++--
 3 files changed, 52 insertions(+), 16 deletions(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 13dfb0a..429e1dd 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -2370,7 +2370,7 @@ static int perf_evsel_browser_title(struct hist_browser 
*browser,
char unit;
int printed;
const struct dso *dso = hists->dso_filter;
-   const struct thread *thread = hists->thread_filter;
+   struct thread *thread = hists->thread_filter;
int socket_id = hists->socket_filter;
unsigned long nr_samples = hists->stats.nr_events[PERF_RECORD_SAMPLE];
u64 nr_events = hists->stats.total_period;
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index b7957da..25830b2 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -45,6 +45,8 @@ struct thread *thread__new(pid_t pid, pid_t tid)
thread->cpu = -1;
INIT_LIST_HEAD(>namespaces_list);
INIT_LIST_HEAD(>comm_list);
+   pthread_mutex_init(>namespaces_lock, NULL);
+   pthread_mutex_init(>comm_lock, NULL);
 
comm_str = malloc(32);
if (!comm_str)
@@ -83,15 +85,21 @@ void thread__delete(struct thread *thread)
map_groups__put(thread->mg);
thread->mg = NULL;
}
+   pthread_mutex_lock(>namespaces_lock);
list_for_each_entry_safe(namespaces, tmp_namespaces,
 >namespaces_list, list) {
list_del(>list);
namespaces__free(namespaces);
}
+   pthread_mutex_unlock(>namespaces_lock);
+
+   pthread_mutex_lock(>comm_lock);
list_for_each_entry_safe(comm, tmp_comm, >comm_list, list) {
list_del(>list);
comm__free(comm);
}
+   pthread_mutex_unlock(>comm_lock);
+
unwind__finish_access(thread);
nsinfo__zput(thread->nsinfo);
 
@@ -128,11 +136,17 @@ struct namespaces *thread__namespaces(const struct thread 
*thread)
 int thread__set_namespaces(struct thread *thread, u64 timestamp,
   struct namespaces_event *event)
 {
-   struct namespaces *new, *curr = thread__namespaces(thread);
+   struct namespaces *new, *curr;
+
+   pthread_mutex_lock(>namespaces_lock);
+
+   curr = thread__namespaces(thread);
 
new = namespaces__new(event);
-   if (!new)
+   if (!new) {
+   pthread_mutex_unlock(>namespaces_lock);
return -ENOMEM;
+   }
 
list_add(>list, >namespaces_list);
 
@@ -146,17 +160,21 @@ int thread__set_namespaces(struct thread *thread, u64 
timestamp,
curr->end_time = timestamp;
}
 
+   pthread_mutex_unlock(>namespaces_lock);
+
return 0;
 }
 
-void thread__namespaces_id(const struct thread *thread,
+void thread__namespaces_id(struct thread *thread,
   u64 *dev, u64 *ino)
 {
struct namespaces *ns;
 
+   pthread_mutex_lock(>namespaces_lock);
ns = thread__namespaces(thread);
*dev = ns ? ns->link_info[CGROUP_NS_INDEX].dev : 0;
*ino = ns ? ns->link_info[CGROUP_NS_INDEX].ino : 0;
+   pthread_mutex_unlock(>namespaces_lock);
 }
 
 struct comm *thread__comm(const struct thread *thread)
@@ -183,17 +201,23 @@ struct comm *thread__exec_comm(const struct thread 
*thread)
 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
   bool exec)
 {
-   struct comm *new, *curr = thread__comm(thread);
+   struct comm *new, *curr;
+   int err = 0;
+
+   pthread_mutex_lock(>comm_lock);
+   curr = thread__comm(thread);
 
/* Override the default :tid entry */
if (!thread->comm_set) {
-   int err = comm__override(curr, str, timestamp, exec);
+   err = comm__override(curr, str, timestamp, exec);
if (err)
-   return err;
+   goto unlock;
} else {
new = comm__new(str, timestamp, exec);
-   if (!new)
-   return -ENOMEM;
+   if (!new) {
+   err = -ENOMEM;
+   goto unlock;
+   }
list_add(>list, >comm_list);
 
if (exec)
@@ -202,7 +226,9 @@ int __thread__set_comm(struct thread *thread, const char 
*str, u64 timestamp,
 
thread->comm_set = true;
 
-   

[PATCH RFC V2 05/10] perf tools: lock to protect thread list

[kan . liang]

From: Kan Liang 

Add two locks to protect namespaces_list and comm_list.

The comm which is used in db-export are not protected. Because the
multithread code will not touch it. It can be added later if required.

Signed-off-by: Kan Liang 
---
 tools/perf/ui/browsers/hists.c |  2 +-
 tools/perf/util/thread.c   | 60 +-
 tools/perf/util/thread.h   |  6 +++--
 3 files changed, 52 insertions(+), 16 deletions(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 13dfb0a..429e1dd 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -2370,7 +2370,7 @@ static int perf_evsel_browser_title(struct hist_browser 
*browser,
char unit;
int printed;
const struct dso *dso = hists->dso_filter;
-   const struct thread *thread = hists->thread_filter;
+   struct thread *thread = hists->thread_filter;
int socket_id = hists->socket_filter;
unsigned long nr_samples = hists->stats.nr_events[PERF_RECORD_SAMPLE];
u64 nr_events = hists->stats.total_period;
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index b7957da..25830b2 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -45,6 +45,8 @@ struct thread *thread__new(pid_t pid, pid_t tid)
thread->cpu = -1;
INIT_LIST_HEAD(>namespaces_list);
INIT_LIST_HEAD(>comm_list);
+   pthread_mutex_init(>namespaces_lock, NULL);
+   pthread_mutex_init(>comm_lock, NULL);
 
comm_str = malloc(32);
if (!comm_str)
@@ -83,15 +85,21 @@ void thread__delete(struct thread *thread)
map_groups__put(thread->mg);
thread->mg = NULL;
}
+   pthread_mutex_lock(>namespaces_lock);
list_for_each_entry_safe(namespaces, tmp_namespaces,
 >namespaces_list, list) {
list_del(>list);
namespaces__free(namespaces);
}
+   pthread_mutex_unlock(>namespaces_lock);
+
+   pthread_mutex_lock(>comm_lock);
list_for_each_entry_safe(comm, tmp_comm, >comm_list, list) {
list_del(>list);
comm__free(comm);
}
+   pthread_mutex_unlock(>comm_lock);
+
unwind__finish_access(thread);
nsinfo__zput(thread->nsinfo);
 
@@ -128,11 +136,17 @@ struct namespaces *thread__namespaces(const struct thread 
*thread)
 int thread__set_namespaces(struct thread *thread, u64 timestamp,
   struct namespaces_event *event)
 {
-   struct namespaces *new, *curr = thread__namespaces(thread);
+   struct namespaces *new, *curr;
+
+   pthread_mutex_lock(>namespaces_lock);
+
+   curr = thread__namespaces(thread);
 
new = namespaces__new(event);
-   if (!new)
+   if (!new) {
+   pthread_mutex_unlock(>namespaces_lock);
return -ENOMEM;
+   }
 
list_add(>list, >namespaces_list);
 
@@ -146,17 +160,21 @@ int thread__set_namespaces(struct thread *thread, u64 
timestamp,
curr->end_time = timestamp;
}
 
+   pthread_mutex_unlock(>namespaces_lock);
+
return 0;
 }
 
-void thread__namespaces_id(const struct thread *thread,
+void thread__namespaces_id(struct thread *thread,
   u64 *dev, u64 *ino)
 {
struct namespaces *ns;
 
+   pthread_mutex_lock(>namespaces_lock);
ns = thread__namespaces(thread);
*dev = ns ? ns->link_info[CGROUP_NS_INDEX].dev : 0;
*ino = ns ? ns->link_info[CGROUP_NS_INDEX].ino : 0;
+   pthread_mutex_unlock(>namespaces_lock);
 }
 
 struct comm *thread__comm(const struct thread *thread)
@@ -183,17 +201,23 @@ struct comm *thread__exec_comm(const struct thread 
*thread)
 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
   bool exec)
 {
-   struct comm *new, *curr = thread__comm(thread);
+   struct comm *new, *curr;
+   int err = 0;
+
+   pthread_mutex_lock(>comm_lock);
+   curr = thread__comm(thread);
 
/* Override the default :tid entry */
if (!thread->comm_set) {
-   int err = comm__override(curr, str, timestamp, exec);
+   err = comm__override(curr, str, timestamp, exec);
if (err)
-   return err;
+   goto unlock;
} else {
new = comm__new(str, timestamp, exec);
-   if (!new)
-   return -ENOMEM;
+   if (!new) {
+   err = -ENOMEM;
+   goto unlock;
+   }
list_add(>list, >comm_list);
 
if (exec)
@@ -202,7 +226,9 @@ int __thread__set_comm(struct thread *thread, const char 
*str, u64 timestamp,
 
thread->comm_set = true;
 
-   return 0;
+unlock:
+