Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1262576

[patch] mm, oom: add comment for why oom_adj exists

Show all headers | View raw

/proc/pid/oom_adj exists solely to avoid breaking existing userspace 
binaries that write to the tunable.

Add a comment in the only possible location within the kernel tree to 
describe the situation and motivation for keeping it around.

Signed-off-by: David Rientjes <rientjes@google.com>
---
 fs/proc/base.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1032,6 +1032,16 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
 }
 
+/*
+ * /proc/pid/oom_adj exists solely for backwards compatibility with previous
+ * kernels.  The effective policy is defined by oom_score_adj, which has a
+ * different scale: oom_adj grew exponentially and oom_score_adj grows linearly.
+ * Values written to oom_adj are simply mapped linearly to oom_score_adj.
+ * Processes that become oom disabled via oom_adj will still be oom disabled
+ * with this implementation.
+ *
+ * oom_adj cannot be removed since existing userspace binaries use it.
+ */
 static ssize_t oom_adj_write(struct file *file, const char __user *buf,
 			     size_t count, loff_t *ppos)
 {
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[patch] mm, oom: add comment for why oom_adj exists David Rientjes <rientjes@google.com> - 2015-11-04 21:40 +0100
  Re: [patch] mm, oom: add comment for why oom_adj exists Michal Hocko <mhocko@kernel.org> - 2015-11-05 11:30 +0100
    Re: [patch] mm, oom: add comment for why oom_adj exists David Rientjes <rientjes@google.com> - 2015-11-05 22:30 +0100

csiph-web