* kus Kusche Klaus <[EMAIL PROTECTED]> wrote: > I'm performing realtime latency tests (for details about the hardware > and software, see my mail "[BUG] 2.6.11: Random SCSI/USB errors when > reading from USB memory stick" erlier today). > > Even when the errors described in my previous mail does not occur, > massive USB stick transfers cause latencies of 1 to 2 milliseconds, > which is way too much for realtime control systems.
do these occur under PREEMPT_RT? If yes, do you get any useful trace if you enable all the tracing options but keep wakeup-timing off: # CONFIG_WAKEUP_TIMING is not set CONFIG_PREEMPT_TRACE=y CONFIG_CRITICAL_PREEMPT_TIMING=y CONFIG_CRITICAL_IRQSOFF_TIMING=y CONFIG_CRITICAL_TIMING=y CONFIG_LATENCY_TIMING=y CONFIG_LATENCY_TRACE=y CONFIG_MCOUNT=y this should catch any type of preempt-off section, irqs-off and preempt_disable() alike. (unless the tracer has a bug.) (WAKEUP_TIMING is useful and lightweight but if all other tracing features are enabled it's a bit pointless, and a bit less accurate.) Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/