github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 17:47:41 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

sched/cache: Allow only 1 thread of the process to calculate the LLC occupancy

Browse Source 
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
This commit is contained in:
Jianyong Wu 2026-05-13 13:39:12 -07:00 committed by Peter Zijlstra
parent 067a313581
commit a2b4cf39d9
2 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sched.h
View File

@ -2423,6 +2423,7 @@ struct sched_cache_stat {
struct sched_cache_time __percpu *pcpu_sched;
raw_spinlock_t lock;
unsigned long epoch;
unsigned long next_scan;
int cpu;
} ____cacheline_aligned_in_smp;

11
kernel/sched/fair.c
View File

@ -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 @@ static void get_scan_cpumasks(cpumask_var_t cpus, struct task_struct *p)
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;