As an experiment, I rebuilt a version of Vyatta using 2.6.26-rt11 kernel. This required some fixes to unionfs and aufs which I'll send to anyone who wants. The performance of the RT PREEMPT kernel is worse than non-PREEMPT kernel. Running RFC2544, frame loss test we the loss rate is worse on RT than non RT. Ideally, there would be no loss, but on this platform, the best we have seen is 70% loss at 64 bytes. Size 2.6.26 2.6.26-rt11 64 80.5% 99% 128 67 99 256 43 92 512 0 54 1024 0 3 1280 0 0 1518 0 0 More importantly, with RT PREEMPT, the driver gets stuck and times out under heavy load (see 99% loss above). It appears the change to network scheduling related to NAPI doesn't work well under load. I wouldn't recommend RT PREEMPT for heavy network loads. Hardware: Celeron 430 @ 1.80GHz Intel dual-port 82546GB NIC Config: CONFIG_NR_CPUS=8 CONFIG_SCHED_SMT=y CONFIG_SCHED_MC=y # CONFIG_PREEMPT_NONE is not set # CONFIG_PREEMPT_VOLUNTARY is not set # CONFIG_PREEMPT_DESKTOP is not set CONFIG_PREEMPT_RT=y CONFIG_PREEMPT=y CONFIG_PREEMPT_SOFTIRQS=y CONFIG_PREEMPT_HARDIRQS=y CONFIG_PREEMPT_RCU=y CONFIG_PREEMPT_RCU_BOOST=y -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
