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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2008-06-18 09:26:49 -0700
committerIngo Molnar <mingo@elte.hu>2008-06-19 11:22:15 +0200
commit31a72bce0bd6f3e0114009288bccbc96376eeeca (patch)
tree14a817fbe0b47511d3119360c47959d48f851140 /kernel
parentd120f65f3aaf306c957bc4c82e510f5b0f1e9b27 (diff)
downloadop-kernel-dev-31a72bce0bd6f3e0114009288bccbc96376eeeca.zip
op-kernel-dev-31a72bce0bd6f3e0114009288bccbc96376eeeca.tar.gz
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')
-rw-r--r--kernel/rcutorture.c9
-rw-r--r--kernel/sysctl.c13
2 files changed, 21 insertions, 1 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 98ae7d1..27003e2 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -125,6 +125,13 @@ static struct list_head rcu_torture_removed;
static int stutter_pause_test = 0;
+#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
+#define RCUTORTURE_RUNNABLE_INIT 1
+#else
+#define RCUTORTURE_RUNNABLE_INIT 0
+#endif
+int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
+
/*
* Allocate an element from the rcu_tortures pool.
*/
@@ -188,7 +195,7 @@ rcu_random(struct rcu_random_state *rrsp)
static void
rcu_stutter_wait(void)
{
- while (stutter_pause_test)
+ while (stutter_pause_test || !rcutorture_runnable)
schedule_timeout_interruptible(1);
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 2911665..c6887cf 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
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