Commit-ID: 6f1982fedd59856bcc42a9b521be4c3ffd2f60a7 Gitweb: https://git.kernel.org/tip/6f1982fedd59856bcc42a9b521be4c3ffd2f60a7 Author: Frederic Weisbecker <frede...@kernel.org> AuthorDate: Fri, 27 Oct 2017 04:42:36 +0200 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 27 Oct 2017 09:55:30 +0200
sched/isolation: Handle the nohz_full= parameter We want to centralize the isolation management, done by the housekeeping subsystem. Therefore we need to handle the nohz_full= parameter from there. Since nohz_full= so far has involved unbound timers, watchdog, RCU and tilegx NAPI isolation, we keep that default behaviour. nohz_full= will be deprecated in the future. We want to control the isolation features from the isolcpus= parameter. Signed-off-by: Frederic Weisbecker <frede...@kernel.org> Acked-by: Thomas Gleixner <t...@linutronix.de> Cc: Chris Metcalf <cmetc...@mellanox.com> Cc: Christoph Lameter <c...@linux.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Luiz Capitulino <lcapitul...@redhat.com> Cc: Mike Galbraith <efa...@gmx.de> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Rik van Riel <r...@redhat.com> Cc: Wanpeng Li <kernel...@gmail.com> Link: http://lkml.kernel.org/r/1509072159-31808-10-git-send-email-frede...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- include/linux/sched/isolation.h | 1 + include/linux/tick.h | 2 ++ init/Kconfig | 1 - kernel/sched/isolation.c | 42 +++++++++++++++++++++++++++++------------ kernel/time/tick-sched.c | 13 +++---------- 5 files changed, 36 insertions(+), 23 deletions(-) diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h index 9bb753e..e53cfa9 100644 --- a/include/linux/sched/isolation.h +++ b/include/linux/sched/isolation.h @@ -10,6 +10,7 @@ enum hk_flags { HK_FLAG_RCU = (1 << 1), HK_FLAG_MISC = (1 << 2), HK_FLAG_SCHED = (1 << 3), + HK_FLAG_TICK = (1 << 4), }; #ifdef CONFIG_CPU_ISOLATION diff --git a/include/linux/tick.h b/include/linux/tick.h index 68afc09..e2a163a 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -228,6 +228,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal, extern void tick_nohz_full_kick_cpu(int cpu); extern void __tick_nohz_task_switch(void); +extern void __init tick_nohz_full_setup(cpumask_var_t cpumask); #else static inline bool tick_nohz_full_enabled(void) { return false; } static inline bool tick_nohz_full_cpu(int cpu) { return false; } @@ -248,6 +249,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal, static inline void tick_nohz_full_kick_cpu(int cpu) { } static inline void __tick_nohz_task_switch(void) { } +static inline void tick_nohz_full_setup(cpumask_var_t cpumask) { } #endif static inline void tick_nohz_task_switch(void) diff --git a/init/Kconfig b/init/Kconfig index 6f52e6f..f8564df 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -474,7 +474,6 @@ endmenu # "CPU/Task time and stats accounting" config CPU_ISOLATION bool "CPU isolation" - depends on NO_HZ_FULL help Make sure that CPUs running critical tasks are not disturbed by any source of "noise" such as unbound workqueues, timers, kthreads... diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 37a138a..1f61e44 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -54,23 +54,41 @@ EXPORT_SYMBOL_GPL(housekeeping_test_cpu); void __init housekeeping_init(void) { - if (!tick_nohz_full_enabled()) + if (!housekeeping_flags) return; - if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) { - WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n"); - cpumask_clear(tick_nohz_full_mask); - tick_nohz_full_running = false; - return; + static_branch_enable(&housekeeping_overriden); + + /* We need at least one CPU to handle housekeeping work */ + WARN_ON_ONCE(cpumask_empty(housekeeping_mask)); +} + +#ifdef CONFIG_NO_HZ_FULL +static int __init housekeeping_nohz_full_setup(char *str) +{ + cpumask_var_t non_housekeeping_mask; + + alloc_bootmem_cpumask_var(&non_housekeeping_mask); + if (cpulist_parse(str, non_housekeeping_mask) < 0) { + pr_warn("Housekeeping: Incorrect nohz_full cpumask\n"); + free_bootmem_cpumask_var(non_housekeeping_mask); + return 0; } - cpumask_andnot(housekeeping_mask, - cpu_possible_mask, tick_nohz_full_mask); + alloc_bootmem_cpumask_var(&housekeeping_mask); + cpumask_andnot(housekeeping_mask, cpu_possible_mask, non_housekeeping_mask); - housekeeping_flags = HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC; + if (cpumask_empty(housekeeping_mask)) + cpumask_set_cpu(smp_processor_id(), housekeeping_mask); - static_branch_enable(&housekeeping_overriden); + housekeeping_flags = HK_FLAG_TICK | HK_FLAG_TIMER | + HK_FLAG_RCU | HK_FLAG_MISC; - /* We need at least one CPU to handle housekeeping work */ - WARN_ON_ONCE(cpumask_empty(housekeeping_mask)); + tick_nohz_full_setup(non_housekeeping_mask); + + free_bootmem_cpumask_var(non_housekeeping_mask); + + return 1; } +__setup("nohz_full=", housekeeping_nohz_full_setup); +#endif diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 27d7d52..69f3dbe 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -385,20 +385,13 @@ out: local_irq_restore(flags); } -/* Parse the boot-time nohz CPU list from the kernel parameters. */ -static int __init tick_nohz_full_setup(char *str) +/* Get the boot-time nohz CPU list from the kernel parameters. */ +void __init tick_nohz_full_setup(cpumask_var_t cpumask) { alloc_bootmem_cpumask_var(&tick_nohz_full_mask); - if (cpulist_parse(str, tick_nohz_full_mask) < 0) { - pr_warn("NO_HZ: Incorrect nohz_full cpumask\n"); - free_bootmem_cpumask_var(tick_nohz_full_mask); - return 1; - } + cpumask_copy(tick_nohz_full_mask, cpumask); tick_nohz_full_running = true; - - return 1; } -__setup("nohz_full=", tick_nohz_full_setup); static int tick_nohz_cpu_down(unsigned int cpu) {
