Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
sched/mmcid: Convert mm CID mask to a bitmap
This is truly a bitmap and just conveniently uses a cpumask because the
maximum size of the bitmap is nr_cpu_ids.
But that prevents to do searches for a zero bit in a limited range, which
is helpful to provide an efficient mechanism to consolidate the CID space
when the number of users decreases.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Link: https://patch.msgid.link/20251119172549.642866767@linutronix.de
+9
-8
+5
-4
include/linux/mm_types.h
+5
-4
include/linux/mm_types.h
···
1342
1342
}
1343
1343
1344
1344
/* Accessor for struct mm_struct's cidmask. */
1345
-
static inline cpumask_t *mm_cidmask(struct mm_struct *mm)
1345
+
static inline unsigned long *mm_cidmask(struct mm_struct *mm)
1346
1346
{
1347
1347
unsigned long cid_bitmap = (unsigned long)mm_cpus_allowed(mm);
1348
1348
1349
1349
/* Skip mm_cpus_allowed */
1350
1350
cid_bitmap += cpumask_size();
1351
-
return (struct cpumask *)cid_bitmap;
1351
+
return (unsigned long *)cid_bitmap;
1352
1352
}
1353
1353
1354
1354
static inline void mm_init_cid(struct mm_struct *mm, struct task_struct *p)
···
1363
1363
mm->mm_cid.nr_cpus_allowed = p->nr_cpus_allowed;
1364
1364
raw_spin_lock_init(&mm->mm_cid.lock);
1365
1365
cpumask_copy(mm_cpus_allowed(mm), &p->cpus_mask);
1366
-
cpumask_clear(mm_cidmask(mm));
1366
+
bitmap_zero(mm_cidmask(mm), num_possible_cpus());
1367
1367
}
1368
1368
1369
1369
static inline int mm_alloc_cid_noprof(struct mm_struct *mm, struct task_struct *p)
···
1384
1384
1385
1385
static inline unsigned int mm_cid_size(void)
1386
1386
{
1387
-
return 2 * cpumask_size(); /* mm_cpus_allowed(), mm_cidmask(). */
1387
+
/* mm_cpus_allowed(), mm_cidmask(). */
1388
+
return cpumask_size() + bitmap_size(num_possible_cpus());
1388
1389
}
1389
1390
1390
1391
#else /* CONFIG_SCHED_MM_CID */
+1
-1
kernel/sched/core.c
+1
-1
kernel/sched/core.c
+3
-3
kernel/sched/sched.h
+3
-3
kernel/sched/sched.h
···
3559
3559
3560
3560
if (cid >= max_cids)
3561
3561
return false;
3562
-
if (cpumask_test_and_set_cpu(cid, mm_cidmask(mm)))
3562
+
if (test_and_set_bit(cid, mm_cidmask(mm)))
3563
3563
return false;
3564
3564
t->mm_cid.cid = t->mm_cid.last_cid = cid;
3565
3565
__this_cpu_write(mm->mm_cid.pcpu->cid, cid);
···
3582
3582
return true;
3583
3583
3584
3584
/* Try the first zero bit in the cidmask. */
3585
-
return __mm_cid_get(t, cpumask_first_zero(mm_cidmask(mm)), max_cids);
3585
+
return __mm_cid_get(t, find_first_zero_bit(mm_cidmask(mm), num_possible_cpus()), max_cids);
3586
3586
}
3587
3587
3588
3588
static inline void mm_cid_select(struct task_struct *t)
···
3603
3603
{
3604
3604
if (prev->mm_cid.active) {
3605
3605
if (prev->mm_cid.cid != MM_CID_UNSET)
3606
-
cpumask_clear_cpu(prev->mm_cid.cid, mm_cidmask(prev->mm));
3606
+
clear_bit(prev->mm_cid.cid, mm_cidmask(prev->mm));
3607
3607
prev->mm_cid.cid = MM_CID_UNSET;
3608
3608
}
3609
3609