Messages in this thread Patch in this message | | | From | Roland McGrath <> | Subject | Re: Fix pacct bug in multithreading case. | Date | Tue, 4 Apr 2006 02:25:07 -0700 (PDT) |
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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(¤t->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/
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