diff mbox series

[v8,4/5] mm,page_owner: Filter out stacks by a threshold

Message ID 20240212223029.30769-5-osalvador@suse.de
State New
Headers
Series page_owner: print stacks and their outstanding allocations |

Commit Message

Oscar Salvador Feb. 12, 2024, 10:30 p.m. UTC 
  We want to be able to filter out the stacks based on a threshold we can
can tune.
By writing to 'set_threshold' file, we can adjust the threshold value.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_owner.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

Comments

Marco Elver Feb. 13, 2024, 8:41 a.m. UTC | #1 
On Mon, 12 Feb 2024 at 23:29, Oscar Salvador <osalvador@suse.de> wrote:
>
> We want to be able to filter out the stacks based on a threshold we can
> can tune.
> By writing to 'set_threshold' file, we can adjust the threshold value.
>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> ---
>  mm/page_owner.c | 24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 3e4b7cd7c8f8..c4f9e5506e93 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -832,15 +832,18 @@ static void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
>         return stack;
>  }
>
> +static unsigned long page_owner_stack_threshold;
> +
>  static int stack_print(struct seq_file *m, void *v)
>  {
>         char *buf;
>         int ret = 0;
>         struct stack *stack = v;
>         struct stack_record *stack_record = stack->stack_record;
> +       int stack_count = refcount_read(&stack_record->count);
>
>         if (!stack_record->size || stack_record->size < 0 ||
> -           refcount_read(&stack_record->count) < 2)
> +           stack_count < 2 || stack_count < page_owner_stack_threshold)
>                 return 0;
>
>         buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
> @@ -851,7 +854,7 @@ static int stack_print(struct seq_file *m, void *v)
>                 goto out;
>
>         scnprintf(buf + ret, PAGE_SIZE - ret, "stack_count: %d\n\n",
> -                 refcount_read(&stack_record->count));
> +                 stack_count);
>
>         seq_printf(m, buf);
>         seq_puts(m, "\n\n");
> @@ -884,6 +887,21 @@ static const struct file_operations page_owner_stack_operations = {
>         .release        = seq_release,
>  };
>
> +static int page_owner_threshold_get(void *data, u64 *val)
> +{
> +       *val = page_owner_stack_threshold;
> +       return 0;
> +}
> +
> +static int page_owner_threshold_set(void *data, u64 val)
> +{
> +       page_owner_stack_threshold = val;

This could be written concurrently, so to avoid data races, you can
use WRITE_ONCE(page_owner_stack_threshold, val) and use
READ_ONCE(page_owner_stack_threshold) where it's read.

> +       return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get,
> +                       &page_owner_threshold_set, "%llu");
> +
>  static int __init pageowner_init(void)
>  {
>         struct dentry *dir;
> @@ -898,6 +916,8 @@ static int __init pageowner_init(void)
>         dir = debugfs_create_dir("page_owner_stacks", NULL);
>         debugfs_create_file("show_stacks", 0400, dir, NULL,
>                             &page_owner_stack_operations);
> +       debugfs_create_file("set_threshold", 0600, dir, NULL,
> +                           &proc_page_owner_threshold);
>
>         return 0;
>  }
> --
> 2.43.0
>
Marco Elver Feb. 13, 2024, 8:44 a.m. UTC | #2 
On Mon, 12 Feb 2024 at 23:29, Oscar Salvador <osalvador@suse.de> wrote:
>
> We want to be able to filter out the stacks based on a threshold we can
> can tune.
> By writing to 'set_threshold' file, we can adjust the threshold value.
>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> ---
>  mm/page_owner.c | 24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 3e4b7cd7c8f8..c4f9e5506e93 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -832,15 +832,18 @@ static void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
>         return stack;
>  }
>
> +static unsigned long page_owner_stack_threshold;
> +
>  static int stack_print(struct seq_file *m, void *v)
>  {
>         char *buf;
>         int ret = 0;
>         struct stack *stack = v;
>         struct stack_record *stack_record = stack->stack_record;
> +       int stack_count = refcount_read(&stack_record->count);
>
>         if (!stack_record->size || stack_record->size < 0 ||
> -           refcount_read(&stack_record->count) < 2)
> +           stack_count < 2 || stack_count < page_owner_stack_threshold)
>                 return 0;
>
>         buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
> @@ -851,7 +854,7 @@ static int stack_print(struct seq_file *m, void *v)
>                 goto out;
>
>         scnprintf(buf + ret, PAGE_SIZE - ret, "stack_count: %d\n\n",
> -                 refcount_read(&stack_record->count));
> +                 stack_count);
>
>         seq_printf(m, buf);
>         seq_puts(m, "\n\n");
> @@ -884,6 +887,21 @@ static const struct file_operations page_owner_stack_operations = {
>         .release        = seq_release,
>  };
>
> +static int page_owner_threshold_get(void *data, u64 *val)
> +{
> +       *val = page_owner_stack_threshold;
> +       return 0;
> +}
> +
> +static int page_owner_threshold_set(void *data, u64 val)
> +{
> +       page_owner_stack_threshold = val;
> +       return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get,
> +                       &page_owner_threshold_set, "%llu");
> +
>  static int __init pageowner_init(void)
>  {
>         struct dentry *dir;
> @@ -898,6 +916,8 @@ static int __init pageowner_init(void)
>         dir = debugfs_create_dir("page_owner_stacks", NULL);
>         debugfs_create_file("show_stacks", 0400, dir, NULL,
>                             &page_owner_stack_operations);
> +       debugfs_create_file("set_threshold", 0600, dir, NULL,
> +                           &proc_page_owner_threshold);

Can't you also read from "set_threshold", so the name "set_threshold"
is misleading. Why not just "threshold"?
Oscar Salvador Feb. 13, 2024, 9:21 a.m. UTC | #3 
On Tue, Feb 13, 2024 at 09:44:47AM +0100, Marco Elver wrote:
> On Mon, 12 Feb 2024 at 23:29, Oscar Salvador <osalvador@suse.de> wrote:
> > +       debugfs_create_file("set_threshold", 0600, dir, NULL,
> > +                           &proc_page_owner_threshold);
> 
> Can't you also read from "set_threshold", so the name "set_threshold"
> is misleading. Why not just "threshold"?

Yes, it can also be read.
I guess I was too focused on the set part.
I will rename that one, plus add the {READ,WRITE}_ONCE.

Thanks!
Vlastimil Babka Feb. 13, 2024, 2:56 p.m. UTC | #4 
On 2/13/24 10:21, Oscar Salvador wrote:
> On Tue, Feb 13, 2024 at 09:44:47AM +0100, Marco Elver wrote:
>> On Mon, 12 Feb 2024 at 23:29, Oscar Salvador <osalvador@suse.de>
>> wrote:
>>> +       debugfs_create_file("set_threshold", 0600, dir, NULL, +
>>> &proc_page_owner_threshold);
>> 
>> Can't you also read from "set_threshold", so the name "set_threshold" 
>> is misleading. Why not just "threshold"?
> 
> Yes, it can also be read. I guess I was too focused on the set part.

Maybe name it "count_threshold" so it's more clear of whate exactly it's the
threshold of?

> I will rename that one, plus add the {READ,WRITE}_ONCE.
> 
> Thanks!
>
diff mbox series

Patch

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 3e4b7cd7c8f8..c4f9e5506e93 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -832,15 +832,18 @@  static void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
 	return stack;
 }
 
+static unsigned long page_owner_stack_threshold;
+
 static int stack_print(struct seq_file *m, void *v)
 {
 	char *buf;
 	int ret = 0;
 	struct stack *stack = v;
 	struct stack_record *stack_record = stack->stack_record;
+	int stack_count = refcount_read(&stack_record->count);
 
 	if (!stack_record->size || stack_record->size < 0 ||
-	    refcount_read(&stack_record->count) < 2)
+	    stack_count < 2 || stack_count < page_owner_stack_threshold)
 		return 0;
 
 	buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
@@ -851,7 +854,7 @@  static int stack_print(struct seq_file *m, void *v)
 		goto out;
 
 	scnprintf(buf + ret, PAGE_SIZE - ret, "stack_count: %d\n\n",
-		  refcount_read(&stack_record->count));
+		  stack_count);
 
 	seq_printf(m, buf);
 	seq_puts(m, "\n\n");
@@ -884,6 +887,21 @@  static const struct file_operations page_owner_stack_operations = {
 	.release	= seq_release,
 };
 
+static int page_owner_threshold_get(void *data, u64 *val)
+{
+	*val = page_owner_stack_threshold;
+	return 0;
+}
+
+static int page_owner_threshold_set(void *data, u64 val)
+{
+	page_owner_stack_threshold = val;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get,
+			&page_owner_threshold_set, "%llu");
+
 static int __init pageowner_init(void)
 {
 	struct dentry *dir;
@@ -898,6 +916,8 @@  static int __init pageowner_init(void)
 	dir = debugfs_create_dir("page_owner_stacks", NULL);
 	debugfs_create_file("show_stacks", 0400, dir, NULL,
 			    &page_owner_stack_operations);
+	debugfs_create_file("set_threshold", 0600, dir, NULL,
+			    &proc_page_owner_threshold);
 
 	return 0;
 }