On Wed, Jul 18, 2007 at 11:09:07PM -0700, Andrew Morton wrote: >On Wed, 18 Jul 2007 22:41:21 -0700 Ravikiran G Thirumalai <[EMAIL PROTECTED]> >wrote: > >> On Wed, Jul 18, 2007 at 04:08:58PM -0700, Andrew Morton wrote: >> > On Mon, 16 Jul 2007 15:26:50 -0700 >> > Ravikiran G Thirumalai <[EMAIL PROTECTED]> wrote: >> > >> > > Kernel warns of softlockups if the softlockup thread is not able to run >> > > on a CPU for 10s. It is useful to lower the softlockup warning >> > > threshold in testing environments to catch potential lockups early. >> > > Following patch adds a kernel parameter 'softlockup_lim' to control >> > > the softlockup threshold. >> > > >> > >> > Why not make it tunable at runtime? >> >> Sure! Like a sysctl? >>
Hi Andrew, Here's another take, incorporating all of your comments. Thanks, Kiran Control the trigger limit for softlockup warnings. This is useful for debugging softlockups, by lowering the softlockup_thresh to identify possible softlockups earlier. This patch: 1. Adds a sysctl softlockup_thresh with valid values of 1-60s (Higher value to disable false positives) 2. Changes the softlockup printk to print the cpu softlockup time Signed-off-by: Ravikiran Thirumalai <[EMAIL PROTECTED]> Signed-off-by: Shai Fultheim <[EMAIL PROTECTED]> --- Patch applies on top of Ingo's softlockup patches Documentation/sysctl/kernel.txt | 8 ++++++++ include/linux/sched.h | 1 + kernel/softlockup.c | 8 +++++--- kernel/sysctl.c | 25 +++++++++++++++++++------ 4 files changed, 33 insertions(+), 9 deletions(-) Index: linux-2.6.22/kernel/softlockup.c =================================================================== --- linux-2.6.22.orig/kernel/softlockup.c 2007-07-18 11:15:18.506614500 -0700 +++ linux-2.6.22/kernel/softlockup.c 2007-07-18 21:39:20.498592750 -0700 @@ -23,6 +23,7 @@ static DEFINE_PER_CPU(unsigned long, pri static DEFINE_PER_CPU(struct task_struct *, watchdog_task); static int did_panic; +int softlockup_thresh = 10; static int softlock_panic(struct notifier_block *this, unsigned long event, void *ptr) @@ -101,7 +102,7 @@ void softlockup_tick(void) wake_up_process(per_cpu(watchdog_task, this_cpu)); /* Warn about unreasonable 10+ seconds delays: */ - if (now <= (touch_timestamp + 10)) + if (now <= (touch_timestamp + softlockup_thresh)) return; regs = get_irq_regs(); @@ -109,8 +110,9 @@ void softlockup_tick(void) per_cpu(print_timestamp, this_cpu) = touch_timestamp; spin_lock(&print_lock); - printk(KERN_ERR "BUG: soft lockup detected on CPU#%d! [%s:%d]\n", - this_cpu, current->comm, current->pid); + printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n", + this_cpu, now - touch_timestamp, + current->comm, current->pid); if (regs) show_regs(regs); else Index: linux-2.6.22/kernel/sysctl.c =================================================================== --- linux-2.6.22.orig/kernel/sysctl.c 2007-07-08 16:32:17.000000000 -0700 +++ linux-2.6.22/kernel/sysctl.c 2007-07-19 13:42:50.275478000 -0700 @@ -79,6 +79,12 @@ extern int compat_log; extern int maps_protect; extern int sysctl_stat_interval; +/* Constants used for minimum and maximum */ +static int one = 1; +static int zero; +static int sixty = 60; +static int one_hundred = 100; + /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */ static int maxolduid = 65535; static int minolduid; @@ -615,16 +621,23 @@ static ctl_table kern_table[] = { .proc_handler = &proc_dointvec, }, #endif +#ifdef CONFIG_DETECT_SOFTLOCKUP + { + .ctl_name = CTL_UNNUMBERED, + .procname = "softlockup_thresh", + .data = &softlockup_thresh, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec_minmax, + .strategy = &sysctl_intvec, + .extra1 = &one, + .extra2 = &sixty, + }, +#endif { .ctl_name = 0 } }; -/* Constants for minimum and maximum testing in vm_table. - We use these as one-element integer vectors. */ -static int zero; -static int one_hundred = 100; - - static ctl_table vm_table[] = { { .ctl_name = VM_OVERCOMMIT_MEMORY, Index: linux-2.6.22/Documentation/sysctl/kernel.txt =================================================================== --- linux-2.6.22.orig/Documentation/sysctl/kernel.txt 2007-07-08 16:32:17.000000000 -0700 +++ linux-2.6.22/Documentation/sysctl/kernel.txt 2007-07-19 13:42:09.748945250 -0700 @@ -320,6 +320,14 @@ kernel. This value defaults to SHMMAX. ============================================================== +softlockup_thresh: + +This value can be used to lower the softlockup tolerance +threshold. The default threshold is 10s. If a cpu is locked up +for 10s, the kernel complains. Valid values are 1-60s. + +============================================================== + tainted: Non-zero if the kernel has been tainted. Numeric values, which Index: linux-2.6.22/include/linux/sched.h =================================================================== --- linux-2.6.22.orig/include/linux/sched.h 2007-07-19 13:35:08.610625750 -0700 +++ linux-2.6.22/include/linux/sched.h 2007-07-19 13:38:57.816950250 -0700 @@ -236,6 +236,7 @@ extern void softlockup_tick(void); extern void spawn_softlockup_task(void); extern void touch_softlockup_watchdog(void); extern void touch_all_softlockup_watchdogs(void); +extern int softlockup_thresh; #else static inline void softlockup_tick(void) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/