R0dn3yS/android_kernel_xiaomi_sm7250
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mm: Perform PID map reads on the little CPU cluster

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PID map reads for processes with thousands of mappings can be done
extensively by certain Android apps, burning through CPU time on
higher-performance CPUs even though reading PID maps is never a
performance-critical task. We can relieve the load on the important CPUs
by moving PID map reads to little CPUs via sched_migrate_to_cpumask_*().

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: dreamisbaka <jolinux.g@gmail.com>
This commit is contained in:
Sultan Alsawaf 2021-05-06 00:00:32 -07:00 committed by spakkkk
parent c2c3304ca2
commit e23d4ea590
2 changed files with 7 additions and 0 deletions
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1
fs/proc/internal.h
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@ -298,6 +298,7 @@ struct proc_maps_private {
#ifdef CONFIG_NUMA
struct mempolicy *task_mempolicy;
#endif
unsigned long old_cpus_allowed;
} __randomize_layout;
struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);

6
fs/proc/task_mmu.c
View File

@ -181,6 +181,9 @@ static void vma_stop(struct proc_maps_private *priv)
release_task_mempolicy(priv);
up_read(&mm->mmap_sem);
mmput(mm);
sched_migrate_to_cpumask_end(to_cpumask(&priv->old_cpus_allowed),
cpu_lp_mask);
}
static struct vm_area_struct *
@ -217,6 +220,9 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
if (!mm || !mmget_not_zero(mm))
return NULL;
sched_migrate_to_cpumask_start(to_cpumask(&priv->old_cpus_allowed),
cpu_lp_mask);
if (down_read_killable(&mm->mmap_sem)) {
mmput(mm);
return ERR_PTR(-EINTR);