Messages in this thread Patch in this message | | | Date | Tue, 29 Jan 2013 10:33:48 -0500 | From | Don Zickus <> | Subject | Re: [BUG?] false positive in soft lockup detector while unlzma initramfs on slow cpu |
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Hi Mike,
On Tue, Jan 29, 2013 at 05:42:43PM +0400, Mike Lykov wrote: > > So my questions: > > 1. Are there a BUG in soft lockup detection mechanizm? Changing > watchdog_thresh to 30 have a side effect in production - D-state > userspace processes will be detected slowly. Are there a need to > detecting soft lockups at boot time? Maybe it need after initramfs > boot only when userspace processes begin to work?
The softlockup mechanism works scheduling a high priority task that kicks the softlockups. If the unzip thread is taking too long, it could accidentally trip the detection.
Seeing that you are running on a 600 MHz machine, it could be possible. Though I am not entirely sure how the scheduling works for decompressing the initramfs. I wouldn't think it is that high of a priority.
> > 2. How to change watchdog_thresh parameter at boot without patching > sources? If it necessary (with it side effects) maybe implement it > as commandline parameter or config compile time parameter?
I attached a patch below that allows you to set it a boot time. Let me know if this works for you, then I can clean it up and post it properly.
Cheers, Don
diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 75a2ab3..e448d63 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -79,6 +79,14 @@ static int __init softlockup_panic_setup(char *str) } __setup("softlockup_panic=", softlockup_panic_setup); +static int __init watchdog_thresh_setup(char *str) +{ + watchdog_thresh = simple_strtoul(str, NULL, 0); + + return 1; +} +__setup("watchdog_thresh=", watchdog_thresh_setup); + static int __init nowatchdog_setup(char *str) { watchdog_enabled = 0;
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