> Hello! Hello Paul, > > At Linus's request, I am simplifying the Linux-kernel RCU implementation, which > includes removing code that implements features and options that are no longer > needed. This is not a half-hearted effort. In fact, I expect that my submission to > the next merge window will be a net removal of more than 2500 lines of code. > > But wait, there is more! ;-) > > Although the following two features are not being axed in v4.13, they will be in > v4.14 unless someone makes a convincing case for them: > > 1. The ability to build a CONFIG_RCU_NOCB_CPUS=y kernel without > also specifying CONFIG_NO_HZ_FULL. > > Unless someone speaks for this configuration option, > CONFIG_RCU_NOCB_CPUS will be slaved off of CONFIG_NO_HZ_FULL, > and the rcu_nocbs= boot parameter will be dropped. (RCU would > instead use the nohz_full= boot parameter to determine which > CPUs get their callbacks offloaded.) We are using CONFIG_RCU_NOCB_CPUS=y without CONFIG_NO_HZ_FULL with 4.9-rt in our products. We are not using CONFIG_NO_HZ_FULL, because its use was not recommended for real time. We set CONFIG_RCU_NOCB_CPUS=y and CONFIG_RCU_NOCB_CPU_ALL=y to reduce the jitter. This configuration showed the minimal jitter with our application. We are not relying on the configuration itself. Our goal is just a minimum jitter. Thus, if CONFIG_NO_HZ_FULL can be used for real time with no negative impact on the jitter, then we can enable this option. @tglx: Is CONFIG_NO_HZ_FULL the preferred choice for real-time kernels? Gerhard -- 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
