[RFC PATCH v1 01/13] mm: add a percpu_pagelist_batch sysctl interface

From: daniel . m . jordan
Date: Wed Jan 31 2018 - 18:15:49 EST


From: Aaron Lu <aaron.lu@xxxxxxxxx>

---
include/linux/mmzone.h | 2 ++
kernel/sysctl.c | 9 +++++++++
mm/page_alloc.c | 40 +++++++++++++++++++++++++++++++++++++++-
3 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 67f2e3c38939..c05529473b80 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -891,6 +891,8 @@ int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
+int percpu_pagelist_batch_sysctl_handler(struct ctl_table *, int,
+ void __user *, size_t *, loff_t *);
int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 557d46728577..1602bc14bf0d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -108,6 +108,7 @@ extern unsigned int core_pipe_limit;
extern int pid_max;
extern int pid_max_min, pid_max_max;
extern int percpu_pagelist_fraction;
+extern int percpu_pagelist_batch;
extern int latencytop_enabled;
extern unsigned int sysctl_nr_open_min, sysctl_nr_open_max;
#ifndef CONFIG_MMU
@@ -1458,6 +1459,14 @@ static struct ctl_table vm_table[] = {
.proc_handler = percpu_pagelist_fraction_sysctl_handler,
.extra1 = &zero,
},
+ {
+ .procname = "percpu_pagelist_batch",
+ .data = &percpu_pagelist_batch,
+ .maxlen = sizeof(percpu_pagelist_batch),
+ .mode = 0644,
+ .proc_handler = percpu_pagelist_batch_sysctl_handler,
+ .extra1 = &zero,
+ },
#ifdef CONFIG_MMU
{
.procname = "max_map_count",
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 76c9688b6a0a..d7078ed68b01 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -130,6 +130,7 @@ unsigned long totalreserve_pages __read_mostly;
unsigned long totalcma_pages __read_mostly;

int percpu_pagelist_fraction;
+int percpu_pagelist_batch;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;

/*
@@ -5544,7 +5545,8 @@ static void pageset_set_high_and_batch(struct zone *zone,
(zone->managed_pages /
percpu_pagelist_fraction));
else
- pageset_set_batch(pcp, zone_batchsize(zone));
+ pageset_set_batch(pcp, percpu_pagelist_batch ?
+ percpu_pagelist_batch : zone_batchsize(zone));
}

static void __meminit zone_pageset_init(struct zone *zone, int cpu)
@@ -7266,6 +7268,42 @@ int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *table, int write,
return ret;
}

+int percpu_pagelist_batch_sysctl_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos)
+{
+ struct zone *zone;
+ int old_percpu_pagelist_batch;
+ int ret;
+
+ mutex_lock(&pcp_batch_high_lock);
+ old_percpu_pagelist_batch = percpu_pagelist_batch;
+
+ ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (!write || ret < 0)
+ goto out;
+
+ /* Sanity checking to avoid pcp imbalance */
+ if (percpu_pagelist_batch <= 0) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* No change? */
+ if (percpu_pagelist_batch == old_percpu_pagelist_batch)
+ goto out;
+
+ for_each_populated_zone(zone) {
+ unsigned int cpu;
+
+ for_each_possible_cpu(cpu)
+ pageset_set_high_and_batch(zone,
+ per_cpu_ptr(zone->pageset, cpu));
+ }
+out:
+ mutex_unlock(&pcp_batch_high_lock);
+ return ret;
+}
+
#ifdef CONFIG_NUMA
int hashdist = HASHDIST_DEFAULT;

--
2.16.1