sched/isolation: Consolidate housekeeping cpumasks that are always identical

The housekeeping cpumasks are only set by two boot commandline
parameters: "nohz_full" and "isolcpus". When there is more than one of
"nohz_full" or "isolcpus", the extra ones must have the same CPU list
or the setup will fail partially.

The HK_TYPE_DOMAIN and HK_TYPE_MANAGED_IRQ types are settable by
"isolcpus" only and their settings can be independent of the other
types. The other housekeeping types are all set by "nohz_full" or
"isolcpus=nohz" without a way to set them individually. So they all
have identical cpumasks.

There is actually no point in having different cpumasks for these
"nohz_full" only housekeeping types. Consolidate these types to use the
same cpumask by aliasing them to the same value. If there is a need to
set any of them independently in the future, we can break them out to
their own cpumasks again.

With this change, the number of cpumasks in the housekeeping structure
drops from 9 to 3. Other than that, there should be no other functional
change.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-4-longman@redhat.com

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 499d5e480882894407631a0a10c02ca630930306..d8501f4709b583b8a1c91574446382f093bccdb1 100644 (file)
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -7,15 +7,21 @@
 #include <linux/tick.h>
 
 enum hk_type {
-       HK_TYPE_TIMER,
-       HK_TYPE_RCU,
-       HK_TYPE_MISC,
-       HK_TYPE_TICK,
        HK_TYPE_DOMAIN,
-       HK_TYPE_WQ,
        HK_TYPE_MANAGED_IRQ,
-       HK_TYPE_KTHREAD,
-       HK_TYPE_MAX
+       HK_TYPE_KERNEL_NOISE,
+       HK_TYPE_MAX,
+
+       /*
+        * The following housekeeping types are only set by the nohz_full
+        * boot commandline option. So they can share the same value.
+        */
+       HK_TYPE_TICK    = HK_TYPE_KERNEL_NOISE,
+       HK_TYPE_TIMER   = HK_TYPE_KERNEL_NOISE,
+       HK_TYPE_RCU     = HK_TYPE_KERNEL_NOISE,
+       HK_TYPE_MISC    = HK_TYPE_KERNEL_NOISE,
+       HK_TYPE_WQ      = HK_TYPE_KERNEL_NOISE,
+       HK_TYPE_KTHREAD = HK_TYPE_KERNEL_NOISE
 };
 
 #ifdef CONFIG_CPU_ISOLATION

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 6a686322ce3cbbc0d641ea52b7cf1128d79fa084..81bc8b329ef17cd3a3f5ae0a20ca02af3a1a69bc 100644 (file)
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -9,14 +9,9 @@
  */
 
 enum hk_flags {
-       HK_FLAG_TIMER           = BIT(HK_TYPE_TIMER),
-       HK_FLAG_RCU             = BIT(HK_TYPE_RCU),
-       HK_FLAG_MISC            = BIT(HK_TYPE_MISC),
-       HK_FLAG_TICK            = BIT(HK_TYPE_TICK),
        HK_FLAG_DOMAIN          = BIT(HK_TYPE_DOMAIN),
-       HK_FLAG_WQ              = BIT(HK_TYPE_WQ),
        HK_FLAG_MANAGED_IRQ     = BIT(HK_TYPE_MANAGED_IRQ),
-       HK_FLAG_KTHREAD         = BIT(HK_TYPE_KTHREAD),
+       HK_FLAG_KERNEL_NOISE    = BIT(HK_TYPE_KERNEL_NOISE),
 };
 
 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
@@ -96,7 +91,7 @@ void __init housekeeping_init(void)
 
        static_branch_enable(&housekeeping_overridden);
 
-       if (housekeeping.flags & HK_FLAG_TICK)
+       if (housekeeping.flags & HK_FLAG_KERNEL_NOISE)
                sched_tick_offload_init();
 
        for_each_set_bit(type, &housekeeping.flags, HK_TYPE_MAX) {
@@ -120,7 +115,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
        unsigned int first_cpu;
        int err = 0;
 
-       if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK)) {
+       if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE)) {
                if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) {
                        pr_warn("Housekeeping: nohz unsupported."
                                " Build with CONFIG_NO_HZ_FULL\n");
@@ -176,7 +171,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
                        housekeeping_setup_type(type, housekeeping_staging);
        }
 
-       if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK))
+       if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE))
                tick_nohz_full_setup(non_housekeeping_mask);
 
        housekeeping.flags |= flags;
@@ -194,8 +189,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
 {
        unsigned long flags;
 
-       flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
-               HK_FLAG_MISC | HK_FLAG_KTHREAD;
+       flags = HK_FLAG_KERNEL_NOISE;
 
        return housekeeping_setup(str, flags);
 }
@@ -214,8 +208,7 @@ static int __init housekeeping_isolcpus_setup(char *str)
                 */
                if (!strncmp(str, "nohz,", 5)) {
                        str += 5;
-                       flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER |
-                                HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD;
+                       flags |= HK_FLAG_KERNEL_NOISE;
                        continue;
                }