lkml.org 
[lkml]   [2006]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRe: Fix pacct bug in multithreading case.
Date
That change looks correct to me, and I see that it's gone in.

It made me think of another issue affecting the accounting records in
related circumstances when the old group leader died after a non-leader exec.
I think this patch addresses that, and along with your patch, gives more
sensible times in all cases.


Thanks,
Roland


[PATCH] Take original leader's start_time in non-leader exec.

The only record we have of the real-time age of a process, regardless of
execs it's done, is start_time. When a non-leader thread exec, the
original start_time of the process is lost. Things looking at the
real-time age of the process are fooled, for example the process
accounting record when the process finally dies. This change makes the
oldest start_time stick around with the process after a non-leader exec.
This way the association between PID and start_time is kept constant,
which seems correct to me.

Signed-off-by: Roland McGrath <roland@redhat.com>

---

fs/exec.c | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)

7cda52efb6ff969f049bc2ab3742b0341e45184a
diff --git a/fs/exec.c b/fs/exec.c
index 0291a68..a45f712 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -678,6 +678,18 @@ static int de_thread(struct task_struct
while (leader->exit_state != EXIT_ZOMBIE)
yield();

+ /*
+ * The only record we have of the real-time age of a
+ * process, regardless of execs it's done, is start_time.
+ * All the past CPU time is accumulated in signal_struct
+ * from sister threads now dead. But in this non-leader
+ * exec, nothing survives from the original leader thread,
+ * whose birth marks the true age of this process now.
+ * When we take on its identity by switching to its PID, we
+ * also take its birthdate (always earlier than our own).
+ */
+ current->start_time = leader->start_time;
+
spin_lock(&leader->proc_lock);
spin_lock(&current->proc_lock);
proc_dentry1 = proc_pid_unhash(current);
--
1.2.4
-
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/

\
 
 \ /
  Last update: 2006-04-04 11:27    [W:0.039 / U:0.692 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site