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

[daniel . m . jordan]

From: Aaron Lu <aaron...@intel.com>

---
 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