Anyone reproduce this problem? Thanks On Wed, Aug 16, 2017 at 12:39 PM, Journey Journey <journeywang123@xxxxxxxxx> wrote: > Thank you all for replying my question. The Details following: > > Kernel Version: 4.4.32 from > https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.4.32.tar.xz > Rt Patch Version: 4.4.32-rt43 from > https://www.kernel.org/pub/linux/kernel/projects/rt/4.4/older/patch-4.4.32-rt43.patch.gz > > Configs as attached, > (1) config.4.4.32 for non rt kernel > (2) config.4.4.32.rt for rt kernel > > Testcase code as attached, > (1) softlockup-nonrt.c for non rt kernel; > (2) softlockup-rt.c for rt kernel, using raw_spinlock > (3) softlockup-rt-fifo.c for rt kernel, using sched_fifo & priority 99 > (4) sample Makefile for building kernel module > > > Test Case 1: non rt kernel + softlockup-nonrt.c > Picture attached nonrt-1.png > The kernel had no response for keyboard input.... > Picture attached nonrt-2.png > After several minutes, the kdump is triggered. > > Test Case 2: rt kernel + softlockup-rt.c > Picture attached rt-1.png > The kernel had no response for keyboard input.... > Hangs forever ........ > > Test Case 3: rt kernel + softlockup-rt-fifo.c > Picture attached rt-2.png > The kernel had no response for keyboard input.... > Hangs forever ........ > > Test Case 4: rt kernel + softlockup-rt-fifo.c + throttling > Picture attached rt-3.png > The kernel had no response for keyboard input.... > Hangs forever ........ > > By the way, my test environment is virtualbox with ubuntu. > Virtualbox Configration: > Picture attached Virtualbox-1.png Virtualbox-2.png Virtualbox-3.png > > crashkernel config > crashkernel=512M > > Please help me, thanks all!! > > > On Wed, Aug 9, 2017 at 11:35 PM, Julia Cartwright <julia@xxxxxx> wrote: >> On Wed, Aug 09, 2017 at 05:05:42PM +0800, Journey Journey wrote: >>> Test case: https://github.com/saiyamd/softlockup_test/blob/master/softlockup_test.c >>> >> >> Please in the future provide more information as to what you are trying >> to do, what it is you are trying, what you are seeing, and why you think >> it's wrong. >> >> Because otherwise, we're forced to reverse engineer your intent. :( >> >> I'm _guessing_ that what you meant to say was: >> >> I have a testcase module that I use that attempts to trigger the >> kernels softlockup detection. Here is a link: >> >> https://github.com/saiyamd/softlockup_test/blob/master/softlockup_test.c >> >> I'm expecting it to fire the softlockup detector and panic the system >> (I use CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC in my test rig), however, >> when I load this module on an RT system, it doesn't appear to trigger >> the softlockup detector![1] >> >> What could be wrong? >> >> If that's what you meant, then the answer is: >> >> The way that you are "hogging" the CPU, on PREEMPT_RT, doesn't prevent >> the kernel from scheduling other tasks in and out (including the >> watchdog thread which pets the watchdog!). >> >> Your test case, effectively is: >> >> spin_lock(&lock) >> while (1) >> printk("..."); >> spin_unlock(&lock) >> >> On RT, spin-lock protected regions are preemptible. When the watchdog >> hrtimer fires and wakes up the softlockup thread, that thread preempts >> the thread stuck in this region and touches the watchdog. This prevents >> the watchdog threshold from being reached. >> >> The good news for you is that it should be entirely possible for you to >> trigger the softlockup detector on RT entirely in usermode. All you'd >> need to do is disable RT throttling, and set a thread SCHED_FIFO w/ prio >> 99 spinning. >> >> Julia >> >> 1: Note: this has nothing to do with Kdump whatsoever. -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
