diff options
| author | Jianyong Wu <wujianyong@hygon.cn> | 2026-05-13 13:39:12 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-05-18 21:33:14 +0200 |
| commit | a2b4cf39d9d333bfeb9262dbaafe3d24d405a5c0 (patch) | |
| tree | 21d11853f2a2590d89c8c14812aed654fdc76d1e /kernel/sched | |
| parent | 067a3135814334a8ea7241faef364cc48c6340bc (diff) | |
sched/cache: Allow only 1 thread of the process to calculate the LLC occupancy
Scanning online CPUs to calculate the occupancy might be
time-consuming. Only allow 1 thread of the process to scan
the CPUs at the same time, which is similar to what
NUMA balance does in task_numa_work().
Signed-off-by: Jianyong Wu <wujianyong@hygon.cn>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/5672b52e588b855b01e5a1a17822f7c6c7237a3d.1778703694.git.tim.c.chen@linux.intel.com
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5f22e5a097cf..a759ea669d74 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1451,6 +1451,7 @@ void mm_init_sched(struct mm_struct *mm, raw_spin_lock_init(&mm->sc_stat.lock); mm->sc_stat.epoch = epoch; mm->sc_stat.cpu = -1; + mm->sc_stat.next_scan = jiffies; /* * The update to mm->sc_stat should not be reordered @@ -1661,6 +1662,7 @@ out: static void task_cache_work(struct callback_head *work) { + unsigned long next_scan, now = jiffies; struct task_struct *p = current; struct mm_struct *mm = p->mm; unsigned long m_a_occ = 0; @@ -1675,6 +1677,15 @@ static void task_cache_work(struct callback_head *work) if (p->flags & PF_EXITING) return; + next_scan = READ_ONCE(mm->sc_stat.next_scan); + if (time_before(now, next_scan)) + return; + + /* only 1 thread is allowed to scan */ + if (!try_cmpxchg(&mm->sc_stat.next_scan, &next_scan, + now + EPOCH_PERIOD)) + return; + if (!zalloc_cpumask_var(&cpus, GFP_KERNEL)) return; |