ftrace_dump() is used for instance by alt-sysrq-z / sysrq_ftrace_dump(). The function itself dumps the whole trace buffer in an irq-off section so no need to talk about max latencies unless this is going to change. The output on the serial is more or less brief and starts with "** 397774 printk messages dropped **" and so I do see only the end of it. Might be okay. Any reason not to use the sync mode + atomic console while ftrace_dump() is in progress? Sebastian