diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2008-06-18 09:26:49 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-06-19 11:22:15 +0200 |
| commit | 31a72bce0bd6f3e0114009288bccbc96376eeeca (patch) | |
| tree | 14a817fbe0b47511d3119360c47959d48f851140 /kernel/sysctl.c | |
| parent | d120f65f3aaf306c957bc4c82e510f5b0f1e9b27 (diff) | |
| download | lwn-31a72bce0bd6f3e0114009288bccbc96376eeeca.tar.gz lwn-31a72bce0bd6f3e0114009288bccbc96376eeeca.zip | |
rcu: make rcutorture more vicious: reinstate boot-time testing
This patch re-institutes the ability to build rcutorture directly into
the Linux kernel. The reason that this capability was removed was that
this could result in your kernel being pretty much useless, as rcutorture
would be running starting from early boot. This problem has been avoided
by (1) making rcutorture run only three seconds of every six by default,
(2) adding a CONFIG_RCU_TORTURE_TEST_RUNNABLE that permits rcutorture
to be quiesced at boot time, and (3) adding a sysctl in /proc named
/proc/sys/kernel/rcutorture_runnable that permits rcutorture to be
quiesced and unquiesced when built into the kernel.
Please note that this /proc file is -not- available when rcutorture
is built as a module. Please also note that to get the earlier
take-no-prisoners behavior, you must use the boot command line to set
rcutorture's "stutter" parameter to zero.
The rcutorture quiescing mechanism is currently quite crude: loops
in each rcutorture process that poll a global variable once per tick.
Suggestions for improvement are welcome. The default action will
be to reduce the polling rate to a few times per second.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sysctl.c')
| -rw-r--r-- | kernel/sysctl.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 29116652dca8..c6887cf135c8 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -82,6 +82,9 @@ extern int maps_protect; extern int sysctl_stat_interval; extern int latencytop_enabled; extern int sysctl_nr_open_min, sysctl_nr_open_max; +#ifdef CONFIG_RCU_TORTURE_TEST +extern int rcutorture_runnable; +#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */ /* Constants used for minimum and maximum */ #if defined(CONFIG_DETECT_SOFTLOCKUP) || defined(CONFIG_HIGHMEM) @@ -813,6 +816,16 @@ static struct ctl_table kern_table[] = { .child = key_sysctls, }, #endif +#ifdef CONFIG_RCU_TORTURE_TEST + { + .ctl_name = CTL_UNNUMBERED, + .procname = "rcutorture_runnable", + .data = &rcutorture_runnable, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, +#endif /* * NOTE: do not add new entries to this table unless you have read * Documentation/sysctl/ctl_unnumbered.txt |