Messages in this thread | | | From | Zhen Lei <> | Subject | [PATCH v5 0/1] rcu/nocb: Delete local variable 'need_rcu_nocb_mask' in rcu_init_nohz() | Date | Thu, 25 Aug 2022 17:23:10 +0800 |
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v4 --> v5: 1. Cancel eliminate rcu_state.nocb_is_setup. It is useful for case 1) below.
Test cases and test results as below: ---------------------------------------------------------------------- | CONFIG_NO_HZ_FULL | CONFIG_RCU_NOCB_CPU_DEFAULT_ALL | cmdline | ---------------------------------------------------------------------- 1) N | N | none | 2) N | N | rcu_nocbs=1-2 | 3) Y | N | nohz_full=1-2 | 4) Y | Y | none | ---------------------------------------------------------------------- 1) [ 1018.082417] rcu-torture:--- End of test: SUCCESS (default) root@genericarmv8:~# dmesg | grep "Offload RCU callbacks"
root@genericarmv8:~# zcat /proc/config.gz | grep NOCB CONFIG_RCU_NOCB_CPU=y # CONFIG_RCU_NOCB_CPU_DEFAULT_ALL is not set root@genericarmv8:~# zcat /proc/config.gz | grep NO_HZ_FULL # CONFIG_NO_HZ_FULL is not set root@genericarmv8:~# cat /proc/cmdline console=ttyS0 earlyprintk=serial root=/dev/sda rw
2) 3) 4) The same to v4.
v3 --> v4: Fix a build warning. - struct cpumask *cpumask = NULL; + const struct cpumask *cpumask = NULL;
v2 --> v3: 1. Eliminate rcu_state.nocb_is_setup 2. Update the code based on the above patch and commit b37a667c6242 ("rcu/nocb: Add an option to offload all CPUs on boot").
Test cases and test results as below:
---------------------------------------------------------------------- | CONFIG_NO_HZ_FULL | CONFIG_RCU_NOCB_CPU_DEFAULT_ALL | cmdline | ---------------------------------------------------------------------- 1) N | N | none | 2) N | N | rcu_nocbs=1-2 | 3) Y | N | nohz_full=1-2 | 4) Y | Y | none | ----------------------------------------------------------------------
1) [ 1085.691770] rcu-torture:--- End of test: SUCCESS: (default) root@genericarmv8:~# dmesg | grep "Offload RCU callbacks" [ 0.000000] rcu: Offload RCU callbacks from CPUs: (none). root@genericarmv8:~# zcat /proc/config.gz | grep NOCB CONFIG_RCU_NOCB_CPU=y # CONFIG_RCU_NOCB_CPU_DEFAULT_ALL is not set root@genericarmv8:~# zcat /proc/config.gz | grep NO_HZ_FULL # CONFIG_NO_HZ_FULL is not set root@genericarmv8:~# cat /proc/cmdline console=ttyAMA0 root=/dev/vda2 crashkernel=256M@ee000000
2) [ 1022.532198] rcu-torture:--- End of test: SUCCESS: (default) root@genericarmv8:~# dmesg | grep "Offload RCU callbacks" [ 0.000000] rcu: Offload RCU callbacks from CPUs: 1-2. root@genericarmv8:~# zcat /proc/config.gz | grep NOCB CONFIG_RCU_NOCB_CPU=y # CONFIG_RCU_NOCB_CPU_DEFAULT_ALL is not set root@genericarmv8:~# zcat /proc/config.gz | grep NO_HZ_FULL # CONFIG_NO_HZ_FULL is not set root@genericarmv8:~# cat /proc/cmdline console=ttyAMA0 root=/dev/vda2 crashkernel=256M@ee000000 rcu_nocbs=1-2
3) [ 1011.714712] rcu-torture:--- End of test: SUCCESS: (default) root@genericarmv8:~# dmesg | grep "Offload RCU callbacks" [ 0.000000] rcu: Offload RCU callbacks from CPUs: 1-2. root@genericarmv8:~# zcat /proc/config.gz | grep NOCB CONFIG_RCU_NOCB_CPU=y # CONFIG_RCU_NOCB_CPU_DEFAULT_ALL is not set root@genericarmv8:~# zcat /proc/config.gz | grep NO_HZ_FULL CONFIG_NO_HZ_FULL=y root@genericarmv8:~# cat /proc/cmdline console=ttyAMA0 root=/dev/vda2 crashkernel=256M@ee000000 nohz_full=1-2
4) [ 1031.047094] rcu-torture:--- End of test: SUCCESS: (default) root@genericarmv8:~# dmesg | grep "Offload RCU callbacks" [ 0.000000] rcu: Offload RCU callbacks from CPUs: 0-3. root@genericarmv8:~# zcat /proc/config.gz | grep NOCB CONFIG_RCU_NOCB_CPU=y CONFIG_RCU_NOCB_CPU_DEFAULT_ALL=y root@genericarmv8:~# zcat /proc/config.gz | grep NO_HZ_FULL CONFIG_NO_HZ_FULL=y root@genericarmv8:~# cat /proc/cmdline console=ttyAMA0 root=/dev/vda2 crashkernel=256M@ee000000
v1 --> v2: Update commit message.
Zhen Lei (1): rcu: Simplify the code logic of rcu_init_nohz()
kernel/rcu/tree_nocb.h | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-)
-- 2.25.1
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