From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> Version 2 --------- * Implement sysctl instead of adding parallel cdata_acct * Call __account_cdata() in __exit_signal() without tsk siglock Description ----------- Currently the cumulative time accounting in Linux is not complete. Due to POSIX POSIX.1-2001, the CPU time of processes is not accounted to the cumulative time of the parents, if the parents ignore SIGCHLD or have set SA_NOCLDWAIT. This behaviour has the major drawback that it is not possible to calculate all consumed CPU time of a system by looking at the current tasks. CPU time can be lost. This patch adds a new sysctl "kernel.full_cdata" that allows to switch between the POSIX behavior and complete cumulative accounting. The default is the POSIX semantics. Signed-off-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> --- Documentation/sysctl/kernel.txt | 12 ++++++++++++ kernel/exit.c | 13 +++++++++---- kernel/sysctl.c | 10 ++++++++++ 3 files changed, 31 insertions(+), 4 deletions(-) --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -247,6 +247,18 @@ see the hostname(1) man page. ============================================================== +full_cdata: + +With "full_cdata = 0" (default) cumulative resource accounting +under Linux is done according to POSIX.1-2001: The resource +counters of processes are not accounted to the cumulative counters +of their parents, if the parents ignore SIGCHLD or have set +SA_NOCLDWAIT. With "full_cdata = 1" it is possible to enforce +that all dead processes without exception are accounted to their +parents. + +============================================================== + hotplug: Path for the hotplug policy agent. --- a/kernel/exit.c +++ b/kernel/exit.c @@ -57,6 +57,8 @@ #include <asm/pgtable.h> #include <asm/mmu_context.h> +int full_cdata_enabled; + static void exit_mm(struct task_struct * tsk); static void __unhash_process(struct task_struct *p, bool group_dead) @@ -77,7 +79,7 @@ static void __unhash_process(struct task static void __account_cdata(struct task_struct *p) { struct cdata *cd, *pcd, *tcd; - unsigned long maxrss; + unsigned long maxrss, flags; cputime_t tgutime, tgstime; /* @@ -104,7 +106,7 @@ static void __account_cdata(struct task_ tcd = &p->signal->cdata_threads; cd = &p->signal->cdata_wait; - spin_lock_irq(&p->real_parent->sighand->siglock); + spin_lock_irqsave(&p->real_parent->sighand->siglock, flags); pcd->utime = cputime_add(pcd->utime, cputime_add(tgutime, @@ -137,7 +139,7 @@ static void __account_cdata(struct task_ pcd->maxrss = maxrss; task_io_accounting_add(&p->real_parent->signal->ioac, &p->ioac); task_io_accounting_add(&p->real_parent->signal->ioac, &p->signal->ioac); - spin_unlock_irq(&p->real_parent->sighand->siglock); + spin_unlock_irqrestore(&p->real_parent->sighand->siglock, flags); } /* @@ -150,6 +152,9 @@ static void __exit_signal(struct task_st struct sighand_struct *sighand; struct tty_struct *uninitialized_var(tty); + if (group_dead && full_cdata_enabled) + __account_cdata(tsk); + sighand = rcu_dereference_check(tsk->sighand, rcu_read_lock_held() || lockdep_tasklist_lock_is_held()); @@ -1292,7 +1297,7 @@ static int wait_task_zombie(struct wait_ * It can be ptraced but not reparented, check * !task_detached() to filter out sub-threads. */ - if (likely(!traced) && likely(!task_detached(p))) + if (likely(!traced) && likely(!task_detached(p)) && !full_cdata_enabled) __account_cdata(p); /* --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -85,6 +85,7 @@ #if defined(CONFIG_SYSCTL) /* External variables not in a header file. */ +extern int full_cdata_enabled; extern int sysctl_overcommit_memory; extern int sysctl_overcommit_ratio; extern int max_threads; @@ -963,6 +964,15 @@ static struct ctl_table kern_table[] = { .proc_handler = proc_dointvec, }, #endif + { + .procname = "full_cdata", + .data = &full_cdata_enabled, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &one, + }, /* * NOTE: do not add new entries to this table unless you have read * Documentation/sysctl/ctl_unnumbered.txt -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html