-----Original Message----- > 在 2020年11月17日 01:00, crash-utility-request@xxxxxxxxxx 写道: > >> While stkptr_to_task does the job of trying to match a stack pointer > >> to a task, it runs through each task's stack to find whether the given > >> SP falls into its range. This can be a very expensive operation, if > >> the vmcore is from a system running too many tasks. It can get even > >> worse when the total number of CPUs on the system is in the order of > >> thousands. Given the expensive nature of the operation, it must be > >> optimized as much as possible. Possible options to optimize: > >> > >> 1) Get min & max of the stack range in first pass and use these > >> values against the given SP to decide whether or not to proceed > >> with stack lookup. > >> 2) Use multithreading to parallely update irq_tasks. > >> 3) Skip stkptr_to_task() when SP is 0 > >> > >> Though option 3 is a low hanging fruit, it significantly improved the > >> time taken between starting crash utility & reaching crash prompt. > >> Implement option 3 to optimize while listing the other two options > >> as TODO items for follow-up. > > It looks like on x86_64 the stkptr_to_task() is not called when starting > > session and I cannot test, but the patch looks safe enough. > > > > Acked-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx> > > > > Lianbo, Bhupesh, this is not a fix but huge improvement for some > > machines or situations, so I'd like to pick it up for crash-7.2.9. > > Agree with you, this improvement looks good. Thanks, applied. https://github.com/crash-utility/crash/commit/46cfe1f5aed3b1950df505d71553c13abab060a6 Kazu > > > Could you ack this? and my patch for the compiler warnings? > > > Yes. After applying your patch, it doesn't reproduce any more. > > Good findings, Kazu. > > Thanks. > Lianbo > > > Thanks, > > Kazu > > -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
