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Date: Wed, 07 Dec 2011 11:52:02 -0500
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: kamezawa.hiroyu@...fujitsu.com
CC: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
akpm@...ux-foundation.org, rientjes@...gle.com, dchinner@...hat.com
Subject: Re: [PATCH] oom: add tracepoints for oom_score_adj
On 12/6/2011 7:54 PM, KAMEZAWA Hiroyuki wrote:
>>>From 28189e4622fd97324893a0b234183f64472a54d6 Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> Date: Wed, 7 Dec 2011 09:58:16 +0900
> Subject: [PATCH] oom: trace point for oom_score_adj
>
> oom_score_adj is set to prevent a task from being killed by OOM-Killer.
> Some daemons sets this value and their children inerit it sometimes.
> Because inheritance of oom_score_adj is done automatically, users
> can be confused at seeing the value and finds it's hard to debug.
>
> This patch adds trace point for oom_score_adj. This adds 3 trace
> points. at
> - update oom_score_adj
> - fork()
> - rename task->comm(typically, exec())
I don't think they have oom specific thing. Can you please add generic fork and
task rename tracepoint instead?
>
> Outputs will be following.
> bash-2404 [006] 199.620841: oom_score_adj_update: task 2404[bash] updates oom_score_ad j=-1000
"task 2404[bash]" don't look good to me.
In almost case, we use either
- [pid] comm
- pid:comm
- comm:pid
- comm-pid (ftrace specific)
Why do we need to introduce alternative printing style?
> bash-2404 [006] 205.861287: oom_score_adj_inherited: new_task=2442 oom_score_adj=-1000
> su-2442 [003] 205.861761: oom_score_task_rename: rename task 2442[bash] to [su] oom_ score_adj=-1000
> su-2442 [003] 205.866737: oom_score_adj_inherited: new_task=2444 oom_score_adj=-1000
> bash-2444 [007] 205.868136: oom_score_task_rename: rename task 2444[su] to [bash] oom_ score_adj=-1000
> bash-2444 [007] 205.870407: oom_score_adj_inherited: new_task=2445 oom_score_adj=-1000
> bash-2445 [001] 205.870975: oom_score_adj_inherited: new_task=2446 oom_score_adj=-1000
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> ---
> fs/exec.c | 5 +++
> fs/proc/base.c | 3 ++
> include/trace/events/oom.h | 80 ++++++++++++++++++++++++++++++++++++++++++++
> kernel/fork.c | 5 +++
> mm/oom_kill.c | 6 +++
> 5 files changed, 99 insertions(+), 0 deletions(-)
> create mode 100644 include/trace/events/oom.h
>
> diff --git a/fs/exec.c b/fs/exec.c
> index ca141db..562a106 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -59,6 +59,8 @@
> #include <asm/uaccess.h>
> #include <asm/mmu_context.h>
> #include <asm/tlb.h>
> +
> +#include <trace/events/oom.h>
> #include "internal.h"
>
> int core_uses_pid;
> @@ -1054,6 +1056,9 @@ void set_task_comm(struct task_struct *tsk, char *buf)
> {
> task_lock(tsk);
>
> + if (tsk->signal->oom_score_adj)
> + trace_oom_score_task_rename(tsk, buf);
> +
> /*
> * Threads may access current->comm without holding
> * the task lock, so write the string carefully.
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 1050b1c..f201e64 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -87,6 +87,7 @@
> #ifdef CONFIG_HARDWALL
> #include <asm/hardwall.h>
> #endif
> +#include <trace/events/oom.h>
> #include "internal.h"
>
> /* NOTE:
> @@ -1166,6 +1167,7 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
> else
> task->signal->oom_score_adj = (oom_adjust * OOM_SCORE_ADJ_MAX) /
> -OOM_DISABLE;
> + trace_oom_score_adj_update(task);
> err_sighand:
> unlock_task_sighand(task, &flags);
> err_task_lock:
> @@ -1253,6 +1255,7 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
> task->signal->oom_score_adj = oom_score_adj;
> if (has_capability_noaudit(current, CAP_SYS_RESOURCE))
> task->signal->oom_score_adj_min = oom_score_adj;
> + trace_oom_score_adj_update(task);
> /*
> * Scale /proc/pid/oom_adj appropriately ensuring that OOM_DISABLE is
> * always attainable.
> diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h
> new file mode 100644
> index 0000000..f5e6f55
> --- /dev/null
> +++ b/include/trace/events/oom.h
> @@ -0,0 +1,80 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM oom
> +
> +#if !defined(_TRACE_OOM_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_OOM_H
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(oom_score_adj_inherited,
> +
> + TP_PROTO(struct task_struct *task),
> +
> + TP_ARGS(task),
> +
> + TP_STRUCT__entry(
> + __field( pid_t, newpid)
> + __field( int, oom_score_adj)
> + ),
> +
> + TP_fast_assign(
> + __entry->newpid = task->pid;
> + __entry->oom_score_adj = task->signal->oom_score_adj;
> + ),
> +
> + TP_printk("new_task=%ld oom_score_adj=%d",
> + __entry->newpid, __entry->oom_score_adj)
> +);
> +
> +TRACE_EVENT(oom_score_task_rename,
> +
> + TP_PROTO(struct task_struct *task, char *comm),
> +
> + TP_ARGS(task, comm),
> +
> + TP_STRUCT__entry(
> + __field( pid_t, pid)
> + __array( char, oldcomm, TASK_COMM_LEN )
> + __array( char, newcomm, TASK_COMM_LEN )
> + __field( int, oom_score_adj)
> + ),
> +
> + TP_fast_assign(
> + __entry->pid = task->pid;
> + memcpy(__entry->oldcomm, task->comm, TASK_COMM_LEN);
> + memcpy(__entry->newcomm, comm, TASK_COMM_LEN);
> + __entry->oom_score_adj = task->signal->oom_score_adj;
> + ),
> +
> + TP_printk("rename task %ld[%s] to [%s] oom_score_adj=%d",
> + __entry->pid, __entry->oldcomm, __entry->newcomm,
> + __entry->oom_score_adj)
> +);
> +
> +TRACE_EVENT(oom_score_adj_update,
> +
> + TP_PROTO(struct task_struct *task),
> +
> + TP_ARGS(task),
> +
> + TP_STRUCT__entry(
> + __field( pid_t, pid)
> + __array( char, comm, TASK_COMM_LEN )
> + __field( int, oom_score_adj)
> + ),
> +
> + TP_fast_assign(
> + __entry->pid = task->pid;
> + memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
> + __entry->oom_score_adj = task->signal->oom_score_adj;
> + ),
> +
> + TP_printk("task %ld[%s] updates oom_score_adj=%d",
> + __entry->pid, __entry->comm, __entry->oom_score_adj)
> +);
> +
> +#endif
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> +
> +
> diff --git a/kernel/fork.c b/kernel/fork.c
> index e20518d..634aa84 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -76,6 +76,7 @@
> #include <asm/tlbflush.h>
>
> #include <trace/events/sched.h>
> +#include <trace/events/oom.h>
>
> /*
> * Protected counters by write_lock_irq(&tasklist_lock)
> @@ -1390,6 +1391,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
> if (clone_flags & CLONE_THREAD)
> threadgroup_fork_read_unlock(current);
> perf_event_fork(p);
> +
> + if (!(clone_flags & CLONE_THREAD) && p->signal->oom_score_adj)
> + trace_oom_score_adj_inherited(p);
> +
> return p;
>
> bad_fork_free_pid:
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index e2e1402..46b6d0a 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -33,6 +33,10 @@
> #include <linux/security.h>
> #include <linux/ptrace.h>
> #include <linux/freezer.h>
> +#include <linux/ftrace.h>
> +
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/oom.h>
>
> int sysctl_panic_on_oom;
> int sysctl_oom_kill_allocating_task;
> @@ -55,6 +59,7 @@ void compare_swap_oom_score_adj(int old_val, int new_val)
> spin_lock_irq(&sighand->siglock);
> if (current->signal->oom_score_adj == old_val)
> current->signal->oom_score_adj = new_val;
> + trace_oom_score_adj_update(current);
> spin_unlock_irq(&sighand->siglock);
> }
>
> @@ -74,6 +79,7 @@ int test_set_oom_score_adj(int new_val)
> spin_lock_irq(&sighand->siglock);
> old_val = current->signal->oom_score_adj;
> current->signal->oom_score_adj = new_val;
> + trace_oom_score_adj_update(current);
> spin_unlock_irq(&sighand->siglock);
>
> return old_val;
--
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