On (04/27/17 12:14), Steven Rostedt wrote: [..] > I tried this patch. It's better because I get the end of the trace, but > I do lose the beginning of it: > > ** 196358 printk messages dropped ** [ 102.321182] perf-5981 0.... 12983650us : d_path <-seq_path many thanks! so we now drop messages from logbuf, not from per-CPU buffers. that "queue printk_deferred irq_work on every online CPU when we bypass per-CPU buffers from NMI" idea *probably* might help here - we need someone to emit messages from the logbuf while we printk from NMI. there is still a possibility that we can drop messages, though, since log_store() from NMI CPU can be much-much faster than call_console_drivers() on other CPU. -ss
