diff mbox series

[v2,1/3] lib: add functions to adjust oom score

Message ID 20211217113751.359613-1-liwang@redhat.com
State Superseded
Headers show
Series [v2,1/3] lib: add functions to adjust oom score | expand

Commit Message

Li Wang Dec. 17, 2021, 11:37 a.m. UTC 
This introduces function to LTP for adjusting the oom_score_adj of
target process, which may be helpful in OOM tests to prevent kernel
killing the main or lib process during test running.

The exported global tst_enable_oom_protection function can be used
at anywhere you want to protect, but please remember that if you
do enable protection on a process($PID) that all the children will
inherit its score and be ignored by OOM Killer as well. So that's
why tst_cancel_oom_protection is recommended to combination in use.

Signed-off-by: Li Wang <liwang@redhat.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
---

Notes:
    Changes v1->v2:
        * Move commit messages to source code comment
        * correct typos

 include/tst_memutils.h | 19 +++++++++++++++++++
 lib/tst_memutils.c     | 29 +++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

Comments

Cyril Hrubis Dec. 17, 2021, 2:36 p.m. UTC | #1 
Hi!
> +/*
> + * Enable OOM protection to prevent process($PID) being killed by OOM Killer.
> + *   echo -1000 >/proc/$PID/oom_score_adj
> + *
> + * Note:
> + *  This exported tst_enable_oom_protection function can be used at anywhere
> + *  you want to protect, but please remember that if you do enable protection
> + *  on a process($PID) that all the children will inherit its score and be
> + *  ignored by OOM Killer as well. So that's why tst_cancel_oom_protection is
> + *  recommended to combination in use.
> + */
> +void tst_enable_oom_protection(pid_t pid);
> +
> +/*
> + * Cancel the OOM protection for the process($PID).
> + *   echo 0 >/proc/$PID/oom_score_adj
> + */
> +void tst_cancel_oom_protection(pid_t pid);

Minor nit: opposite of enable is disable not cancel.

>  #endif /* TST_MEMUTILS_H__ */
> diff --git a/lib/tst_memutils.c b/lib/tst_memutils.c
> index bd09cf6fa..d97b35007 100644
> --- a/lib/tst_memutils.c
> +++ b/lib/tst_memutils.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2020 SUSE LLC <mdoucha@suse.cz>
>   */
>  
> +#include <stdio.h>
>  #include <unistd.h>
>  #include <limits.h>
>  #include <sys/sysinfo.h>
> @@ -91,3 +92,31 @@ long long tst_available_mem(void)
>  
>  	return mem_available;
>  }
> +
> +static void set_oom_score_adj(pid_t pid, int value)
> +{
> +	int val;
> +	char score_path[64];
> +
> +	if (access("/proc/self/oom_score_adj", F_OK) == -1) {
> +		tst_res(TINFO, "Warning: oom_score_adj does not exist");
> +		return;
> +	}
> +
> +	sprintf(score_path, "/proc/%d/oom_score_adj", pid);
> +	SAFE_FILE_PRINTF(score_path, "%d", value);
> +
> +	SAFE_FILE_SCANF(score_path, "%d", &val);
> +	if (val != value)
> +		tst_brk(TBROK, "oom_score_adj = %d, but expect %d.", val, value);
> +}
> +
> +void tst_enable_oom_protection(pid_t pid)
> +{
> +	set_oom_score_adj(pid, -1000);
> +}
> +
> +void tst_cancel_oom_protection(pid_t pid)
> +{
> +	set_oom_score_adj(pid, 0);
> +}
> -- 
> 2.31.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp
diff mbox series

Patch

diff --git a/include/tst_memutils.h b/include/tst_memutils.h
index f605f544e..dc18df6d2 100644
--- a/include/tst_memutils.h
+++ b/include/tst_memutils.h
@@ -25,4 +25,23 @@  void tst_pollute_memory(size_t maxsize, int fillchar);
  */
 long long tst_available_mem(void);
 
+/*
+ * Enable OOM protection to prevent process($PID) being killed by OOM Killer.
+ *   echo -1000 >/proc/$PID/oom_score_adj
+ *
+ * Note:
+ *  This exported tst_enable_oom_protection function can be used at anywhere
+ *  you want to protect, but please remember that if you do enable protection
+ *  on a process($PID) that all the children will inherit its score and be
+ *  ignored by OOM Killer as well. So that's why tst_cancel_oom_protection is
+ *  recommended to combination in use.
+ */
+void tst_enable_oom_protection(pid_t pid);
+
+/*
+ * Cancel the OOM protection for the process($PID).
+ *   echo 0 >/proc/$PID/oom_score_adj
+ */
+void tst_cancel_oom_protection(pid_t pid);
+
 #endif /* TST_MEMUTILS_H__ */
diff --git a/lib/tst_memutils.c b/lib/tst_memutils.c
index bd09cf6fa..d97b35007 100644
--- a/lib/tst_memutils.c
+++ b/lib/tst_memutils.c
@@ -3,6 +3,7 @@ 
  * Copyright (c) 2020 SUSE LLC <mdoucha@suse.cz>
  */
 
+#include <stdio.h>
 #include <unistd.h>
 #include <limits.h>
 #include <sys/sysinfo.h>
@@ -91,3 +92,31 @@  long long tst_available_mem(void)
 
 	return mem_available;
 }
+
+static void set_oom_score_adj(pid_t pid, int value)
+{
+	int val;
+	char score_path[64];
+
+	if (access("/proc/self/oom_score_adj", F_OK) == -1) {
+		tst_res(TINFO, "Warning: oom_score_adj does not exist");
+		return;
+	}
+
+	sprintf(score_path, "/proc/%d/oom_score_adj", pid);
+	SAFE_FILE_PRINTF(score_path, "%d", value);
+
+	SAFE_FILE_SCANF(score_path, "%d", &val);
+	if (val != value)
+		tst_brk(TBROK, "oom_score_adj = %d, but expect %d.", val, value);
+}
+
+void tst_enable_oom_protection(pid_t pid)
+{
+	set_oom_score_adj(pid, -1000);
+}
+
+void tst_cancel_oom_protection(pid_t pid)
+{
+	set_oom_score_adj(pid, 0);
+}