Hi, guys. I have implemented a low-overhead method for detecting interrupt storm in softlockup. Please review it, all comments are welcome.
Changes from v12 to v13: - Update patch #1 based on the latest kernel code. - From Thomas, split patch #1 into two. The new patch #1 converts kstat_irqs into a struct with just the count in it; the new patch #2 introduces a snapshot mechanism for interrupt statistics. Due to the code being split, I removed the Reviewed-by tags from LiuSong and Douglas in patch #1 and patch #2. Please review it again, and all comments are welcome. - Revised the comment for using printk() instead of pr_crit() to make the reasoning clearer. Changes from v11 to v12: - From Douglas and Thomas, add a new kconfig knob save memory when the softlock detector code is not enabled. - Adjust the order of the patches; patch #1 and patch #2 are related to genirq, while patch #3 and patch #4 are related to watchdog/softlockup, making the dependency relationships clearer. - Add the 'Reviewed-by' tag of Douglas. Changes from v10 to v11: - Only patch #2 and patch #3 have been changed. - Add comments to explain each field of 'struct irqstat' in patch #2. - Split the inner summation logic out of kstat_irqs() and encapsulate it into kstat_irqs_desc() in patch #3. - Adopt Thomas's change log for patch #3. - Add the 'Reviewed-by' tag of Liu Song. Changes from v9 to v10: - The two patches related to 'watchdog/softlockup' remain unchanged. - The majority of the work related to 'genirq' is contributed by Thomas, indicated by adding 'Originally-by' tag. And I'd like to express my gratitude for Thomas's contributions and guidance here. - Adopt Thomas's change log for the snapshot mechanism for interrupt statistics. - Split unrelated change in patch #2 into a separate patch #3. Changes from v8 to v9: - Patch #1 remains unchanged. - From Thomas Gleixner, split patch #2 into two patches. Interrupt infrastructure first and then the actual usage site in the watchdog code. Changes from v7 to v8: - From Thomas Gleixner, implement statistics within the interrupt core code and provide sensible interfaces for the watchdog code. - Patch #1 remains unchanged. Patch #2 has significant changes based on Thomas's suggestions, which is why I have removed Liu Song and Douglas's Reviewed-by from patch #2. Please review it again, and all comments are welcome. Changes from v6 to v7: - Remove "READ_ONCE" in "start_counting_irqs" - Replace the hard-coded 5 with "NUM_SAMPLE_PERIODS" macro in "set_sample_period". - Add empty lines to help with reading the code. - Remove the branch that processes IRQs where "counts_diff = 0". - Add the Reviewed-by of Liu Song and Douglas. Changes from v5 to v6: - Use "./scripts/checkpatch.pl --strict" to get a few extra style nits and fix them. - Squash patch #3 into patch #1, and wrapp the help text to 80 columns. - Sort existing headers alphabetically in watchdog.c - Drop "softlockup_hardirq_cpus", just read "hardirq_counts" and see if it's non-NULL. - Store "nr_irqs" in a local variable. - Simplify the calculation of "cpu_diff". Changes from v4 to v5: - Rearranging variable placement to make code look neater. Changes from v3 to v4: - Renaming some variable and function names to make the code logic more readable. - Change the code location to avoid predeclaring. - Just swap rather than a double loop in tabulate_irq_count. - Since nr_irqs has the potential to grow at runtime, bounds-check logic has been implemented. - Add SOFTLOCKUP_DETECTOR_INTR_STORM Kconfig knob. Changes from v2 to v3: - From Liu Song, using enum instead of macro for cpu_stats, shortening the name 'idx_to_stat' to 'stats', adding 'get_16bit_precesion' instead of using right shift operations, and using 'struct irq_counts'. - From kernel robot test, using '__this_cpu_read' and '__this_cpu_write' instead of accessing to an per-cpu array directly, in order to avoid this warning. 'sparse: incorrect type in initializer (different modifiers)' Changes from v1 to v2: - From Douglas, optimize the memory of cpustats. With the maximum number of CPUs, that's now this. 2 * 8192 * 4 + 1 * 8192 * 5 * 4 + 1 * 8192 = 237,568 bytes. - From Liu Song, refactor the code format and add necessary comments. - From Douglas, use interrupt counts instead of interrupt time to determine the cause of softlockup. - Remove the cmdline parameter added in PATCHv1. Bitao Hu (5): genirq: Convert kstat_irqs to a struct genirq: Provide a snapshot mechanism for interrupt statistics genirq: Avoid summation loops for /proc/interrupts watchdog/softlockup: low-overhead detection of interrupt storm watchdog/softlockup: report the most frequent interrupts arch/mips/dec/setup.c | 2 +- arch/parisc/kernel/smp.c | 2 +- arch/powerpc/kvm/book3s_hv_rm_xics.c | 2 +- include/linux/irqdesc.h | 16 +- include/linux/kernel_stat.h | 8 + kernel/irq/Kconfig | 4 + kernel/irq/internals.h | 4 +- kernel/irq/irqdesc.c | 50 +++++-- kernel/irq/proc.c | 9 +- kernel/watchdog.c | 215 ++++++++++++++++++++++++++- lib/Kconfig.debug | 14 ++ scripts/gdb/linux/interrupts.py | 6 +- 12 files changed, 302 insertions(+), 30 deletions(-) -- 2.37.1 (Apple Git-137.1)
