On Tue, Feb 14, 2017 at 05:09:30PM +0100, peter.enderb...@sonymobile.com wrote:
> From: Peter Enderborg <peter.enderb...@sonymobile.com>
> 
> This collects stats for shrinker calls and how much
> waste work we do within the lowmemorykiller.
> 
> Signed-off-by: Peter Enderborg <peter.enderb...@sonymobile.com>
> ---
>  drivers/staging/android/Kconfig                 | 11 ++++
>  drivers/staging/android/Makefile                |  1 +
>  drivers/staging/android/lowmemorykiller.c       |  9 ++-
>  drivers/staging/android/lowmemorykiller_stats.c | 85 
> +++++++++++++++++++++++++
>  drivers/staging/android/lowmemorykiller_stats.h | 29 +++++++++
>  5 files changed, 134 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/staging/android/lowmemorykiller_stats.c
>  create mode 100644 drivers/staging/android/lowmemorykiller_stats.h
> 
> diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
> index 6c00d6f..96e86c7 100644
> --- a/drivers/staging/android/Kconfig
> +++ b/drivers/staging/android/Kconfig
> @@ -24,6 +24,17 @@ config ANDROID_LOW_MEMORY_KILLER
>         scripts (/init.rc), and it defines priority values with minimum free 
> memory size
>         for each priority.
>  
> +config ANDROID_LOW_MEMORY_KILLER_STATS
> +     bool "Android Low Memory Killer: collect statistics"
> +     depends on ANDROID_LOW_MEMORY_KILLER
> +     default n
> +     help
> +       Create a file in /proc/lmkstats that includes
> +       collected statistics about kills, scans and counts
> +       and  interaction with the shrinker. Its content
> +       will be different depeding on lmk implementation used.

Ick, no new /proc files please, this isn't a "process" value.  What's
wrong with debugfs?

Also note the minor '  ' usage in your first sentence of the help text.

>  source "drivers/staging/android/ion/Kconfig"
>  
>  endif # if ANDROID
> diff --git a/drivers/staging/android/Makefile 
> b/drivers/staging/android/Makefile
> index 7ed1be7..d710eb2 100644
> --- a/drivers/staging/android/Makefile
> +++ b/drivers/staging/android/Makefile
> @@ -4,3 +4,4 @@ obj-y                                 += ion/
>  
>  obj-$(CONFIG_ASHMEM)                 += ashmem.o
>  obj-$(CONFIG_ANDROID_LOW_MEMORY_KILLER)      += lowmemorykiller.o
> +obj-$(CONFIG_ANDROID_LOW_MEMORY_KILLER_STATS)        += 
> lowmemorykiller_stats.o
> diff --git a/drivers/staging/android/lowmemorykiller.c 
> b/drivers/staging/android/lowmemorykiller.c
> index ec3b665..15c1b38 100644
> --- a/drivers/staging/android/lowmemorykiller.c
> +++ b/drivers/staging/android/lowmemorykiller.c
> @@ -42,6 +42,7 @@
>  #include <linux/rcupdate.h>
>  #include <linux/profile.h>
>  #include <linux/notifier.h>
> +#include "lowmemorykiller_stats.h"
>  
>  static u32 lowmem_debug_level = 1;
>  static short lowmem_adj[6] = {
> @@ -72,6 +73,7 @@ static unsigned long lowmem_deathpending_timeout;
>  static unsigned long lowmem_count(struct shrinker *s,
>                                 struct shrink_control *sc)
>  {
> +     lmk_inc_stats(LMK_COUNT);
>       return global_node_page_state(NR_ACTIVE_ANON) +
>               global_node_page_state(NR_ACTIVE_FILE) +
>               global_node_page_state(NR_INACTIVE_ANON) +
> @@ -95,6 +97,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct 
> shrink_control *sc)
>                               global_node_page_state(NR_SHMEM) -
>                               total_swapcache_pages();
>  
> +     lmk_inc_stats(LMK_SCAN);
>       if (lowmem_adj_size < array_size)
>               array_size = lowmem_adj_size;
>       if (lowmem_minfree_size < array_size)
> @@ -134,6 +137,7 @@ static unsigned long lowmem_scan(struct shrinker *s, 
> struct shrink_control *sc)
>               if (task_lmk_waiting(p) &&
>                   time_before_eq(jiffies, lowmem_deathpending_timeout)) {
>                       task_unlock(p);
> +                     lmk_inc_stats(LMK_TIMEOUT);
>                       rcu_read_unlock();
>                       return 0;
>               }
> @@ -179,7 +183,9 @@ static unsigned long lowmem_scan(struct shrinker *s, 
> struct shrink_control *sc)
>                            other_free * (long)(PAGE_SIZE / 1024));
>               lowmem_deathpending_timeout = jiffies + HZ;
>               rem += selected_tasksize;
> -     }
> +             lmk_inc_stats(LMK_KILL);
> +     } else
> +             lmk_inc_stats(LMK_WASTE);
>  
>       lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
>                    sc->nr_to_scan, sc->gfp_mask, rem);
> @@ -196,6 +202,7 @@ static struct shrinker lowmem_shrinker = {
>  static int __init lowmem_init(void)
>  {
>       register_shrinker(&lowmem_shrinker);
> +     init_procfs_lmk();
>       return 0;
>  }
>  device_initcall(lowmem_init);
> diff --git a/drivers/staging/android/lowmemorykiller_stats.c 
> b/drivers/staging/android/lowmemorykiller_stats.c
> new file mode 100644
> index 0000000..673691c
> --- /dev/null
> +++ b/drivers/staging/android/lowmemorykiller_stats.c
> @@ -0,0 +1,85 @@
> +/*
> + *  lowmemorykiller_stats
> + *
> + *  Copyright (C) 2017 Sony Mobile Communications Inc.
> + *
> + *  Author: Peter Enderborg <peter.enderb...@sonymobile.com>
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License version 2 as
> + *  published by the Free Software Foundation.
> + */
> +/* This code is bookkeeping of statistical information
> + * from lowmemorykiller and provide a node in proc "/proc/lmkstats".
> + */
> +
> +#include <linux/proc_fs.h>
> +#include <linux/seq_file.h>
> +#include "lowmemorykiller_stats.h"
> +
> +struct lmk_stats {
> +     atomic_long_t scans; /* counter as in shrinker scans */
> +     atomic_long_t kills; /* the number of sigkills sent */
> +     atomic_long_t waste; /* the numer of extensive calls that did
> +                           * not lead to anything
> +                           */
> +     atomic_long_t timeout; /* counter for shrinker calls that needed
> +                             * to be cancelled due to pending kills
> +                             */
> +     atomic_long_t count; /* number of shrinker count calls */
> +     atomic_long_t unknown; /* internal */

Why not document the structure in the proper kernel-doc format?

Also, do you really need atomic variables here?

> +} st;
> +
> +void lmk_inc_stats(int key)
> +{
> +     switch (key) {
> +     case LMK_SCAN:
> +             atomic_long_inc(&st.scans);
> +             break;
> +     case LMK_KILL:
> +             atomic_long_inc(&st.kills);
> +             break;
> +     case LMK_WASTE:
> +             atomic_long_inc(&st.waste);
> +             break;
> +     case LMK_TIMEOUT:
> +             atomic_long_inc(&st.timeout);
> +             break;
> +     case LMK_COUNT:
> +             atomic_long_inc(&st.count);
> +             break;
> +     default:
> +             atomic_long_inc(&st.unknown);
> +             break;
> +     }
> +}
> +
> +static int lmk_proc_show(struct seq_file *m, void *v)
> +{
> +     seq_printf(m, "kill: %ld\n", atomic_long_read(&st.kills));
> +     seq_printf(m, "scan: %ld\n", atomic_long_read(&st.scans));
> +     seq_printf(m, "waste: %ld\n", atomic_long_read(&st.waste));
> +     seq_printf(m, "timeout: %ld\n", atomic_long_read(&st.timeout));
> +     seq_printf(m, "count: %ld\n", atomic_long_read(&st.count));
> +     seq_printf(m, "unknown: %ld (internal)\n",
> +                atomic_long_read(&st.unknown));
> +
> +     return 0;
> +}
> +
> +static int lmk_proc_open(struct inode *inode, struct file *file)
> +{
> +     return single_open(file, lmk_proc_show, PDE_DATA(inode));
> +}
> +
> +static const struct file_operations lmk_proc_fops = {
> +     .open           = lmk_proc_open,
> +     .read           = seq_read,
> +     .release        = single_release
> +};
> +
> +int __init init_procfs_lmk(void)
> +{
> +     proc_create_data(LMK_PROCFS_NAME, 0444, NULL, &lmk_proc_fops, NULL);
> +     return 0;
> +}
> diff --git a/drivers/staging/android/lowmemorykiller_stats.h 
> b/drivers/staging/android/lowmemorykiller_stats.h
> new file mode 100644
> index 0000000..abeb6924
> --- /dev/null
> +++ b/drivers/staging/android/lowmemorykiller_stats.h
> @@ -0,0 +1,29 @@
> +/*
> + *  lowmemorykiller_stats interface
> + *
> + *  Copyright (C) 2017 Sony Mobile Communications Inc.
> + *
> + *  Author: Peter Enderborg <peter.enderb...@sonymobile.com>
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License version 2 as
> + *  published by the Free Software Foundation.
> + */
> +
> +enum  lmk_kill_stats {

nit, two spaces?

> +     LMK_SCAN = 1,
> +     LMK_KILL = 2,
> +     LMK_WASTE = 3,
> +     LMK_TIMEOUT = 4,
> +     LMK_COUNT = 5
> +};
> +
> +#define LMK_PROCFS_NAME "lmkstats"

You only use it once, why create a #define?  Anyway, debugfs is better
for debugging stuff like this, that is what it was created for.

thanks,

greg k-h
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