Messages in this thread | | | From | Uladzislau Rezki <> | Date | Mon, 11 Apr 2022 15:49:06 +0200 | Subject | Re: [PATCH RFC] rcu/nocb: Provide default all-CPUs mask for RCU_NOCB_CPU=y |
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Hello, Joel.
> On systems with CONFIG_RCU_NOCB_CPU=y, there is no default mask provided > which ends up not offloading any CPU. This patch removes yet another > dependency from the bootloader having to know about RCU, about how many > CPUs the system has, and about how to provide the mask. Basically, I > think we should stop pretending that the user knows what they are doing :). > In other words, if NO_CB_CPU is enabled, lets make use of it. > Could you also please modify the documentation accordingly and send v2?
<snip> urezki@pc638:~/data/raid0/coding/linux-rcu.git$ grep -rn RCU_NOCB_CPU ./Documentation/ ./Documentation/timers/no_hz.rst:188:using the CONFIG_RCU_NOCB_CPU=y Kconfig option. The specific CPUs to ./Documentation/admin-guide/kernel-parameters.txt:4380: In kernels built with CONFIG_RCU_NOCB_CPU=y, ./Documentation/admin-guide/kernel-parameters.txt:4507: When RCU_NOCB_CPU is set, also adjust the ./Documentation/admin-guide/kernel-per-CPU-kthreads.rst:311:3. Build with CONFIG_RCU_NOCB_CPU=y and boot with the rcu_nocbs= ./Documentation/admin-guide/kernel-per-CPU-kthreads.rst:331:2. Build with CONFIG_RCU_NOCB_CPU=n, which will prevent these ./Documentation/RCU/Design/Requirements/Requirements.rst:1424:``CONFIG_RCU_NOCB_CPU=y`` and booted with ``rcu_nocbs=1-63``, where urezki@pc638:~/data/raid0/coding/linux-rcu.git$ grep -rn RCU_NOCB_CPU ./kernel/rcu/ ... ./kernel/rcu/Kconfig:198:config RCU_NOCB_CPU .. <snip>
-- Uladzislau Rezki
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