Revert "mm, page_alloc: only use per-cpu allocator for irq-safe requests"
This reverts commit 374ad05ab64.
While the patch worked great for userspace allocations, the fact that
softirq loses the per-cpu allocator caused problems. It needs to be
redone taking into account that a separate list is needed for hard/soft
IRQs or alternatively find a cheap way of detecting reentry due to an
interrupt. Both are possible but sufficiently tricky that it shouldn't
be rushed.
Jesper had one method for allowing softirqs but reported that the cost
was high enough that it performed similarly to a plain revert. His
figures for netperf TCP_STREAM were as follows
Baseline v4.10.0 : 60316 Mbit/s
Current 4.11.0-rc6: 47491 Mbit/s
Jesper's patch : 60662 Mbit/s
This patch : 60106 Mbit/s
As this is a regression, I wish to revert to noirq allocator for now and
go back to the drawing board.
Link: http://lkml.kernel.org/r/20170415145350.ixy7vtrzdzve57mh@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Tariq Toukan <ttoukan.linux@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f3d603c..07efbc3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1090,10 +1090,10 @@
{
int migratetype = 0;
int batch_free = 0;
- unsigned long nr_scanned, flags;
+ unsigned long nr_scanned;
bool isolated_pageblocks;
- spin_lock_irqsave(&zone->lock, flags);
+ spin_lock(&zone->lock);
isolated_pageblocks = has_isolate_pageblock(zone);
nr_scanned = node_page_state(zone->zone_pgdat, NR_PAGES_SCANNED);
if (nr_scanned)
@@ -1142,7 +1142,7 @@
trace_mm_page_pcpu_drain(page, 0, mt);
} while (--count && --batch_free && !list_empty(list));
}
- spin_unlock_irqrestore(&zone->lock, flags);
+ spin_unlock(&zone->lock);
}
static void free_one_page(struct zone *zone,
@@ -1150,9 +1150,8 @@
unsigned int order,
int migratetype)
{
- unsigned long nr_scanned, flags;
- spin_lock_irqsave(&zone->lock, flags);
- __count_vm_events(PGFREE, 1 << order);
+ unsigned long nr_scanned;
+ spin_lock(&zone->lock);
nr_scanned = node_page_state(zone->zone_pgdat, NR_PAGES_SCANNED);
if (nr_scanned)
__mod_node_page_state(zone->zone_pgdat, NR_PAGES_SCANNED, -nr_scanned);
@@ -1162,7 +1161,7 @@
migratetype = get_pfnblock_migratetype(page, pfn);
}
__free_one_page(page, pfn, zone, order, migratetype);
- spin_unlock_irqrestore(&zone->lock, flags);
+ spin_unlock(&zone->lock);
}
static void __meminit __init_single_page(struct page *page, unsigned long pfn,
@@ -1240,6 +1239,7 @@
static void __free_pages_ok(struct page *page, unsigned int order)
{
+ unsigned long flags;
int migratetype;
unsigned long pfn = page_to_pfn(page);
@@ -1247,7 +1247,10 @@
return;
migratetype = get_pfnblock_migratetype(page, pfn);
+ local_irq_save(flags);
+ __count_vm_events(PGFREE, 1 << order);
free_one_page(page_zone(page), page, pfn, order, migratetype);
+ local_irq_restore(flags);
}
static void __init __free_pages_boot_core(struct page *page, unsigned int order)
@@ -2219,9 +2222,8 @@
int migratetype, bool cold)
{
int i, alloced = 0;
- unsigned long flags;
- spin_lock_irqsave(&zone->lock, flags);
+ spin_lock(&zone->lock);
for (i = 0; i < count; ++i) {
struct page *page = __rmqueue(zone, order, migratetype);
if (unlikely(page == NULL))
@@ -2257,7 +2259,7 @@
* pages added to the pcp list.
*/
__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
- spin_unlock_irqrestore(&zone->lock, flags);
+ spin_unlock(&zone->lock);
return alloced;
}
@@ -2485,20 +2487,17 @@
{
struct zone *zone = page_zone(page);
struct per_cpu_pages *pcp;
+ unsigned long flags;
unsigned long pfn = page_to_pfn(page);
int migratetype;
- if (in_interrupt()) {
- __free_pages_ok(page, 0);
- return;
- }
-
if (!free_pcp_prepare(page))
return;
migratetype = get_pfnblock_migratetype(page, pfn);
set_pcppage_migratetype(page, migratetype);
- preempt_disable();
+ local_irq_save(flags);
+ __count_vm_event(PGFREE);
/*
* We only track unmovable, reclaimable and movable on pcp lists.
@@ -2515,7 +2514,6 @@
migratetype = MIGRATE_MOVABLE;
}
- __count_vm_event(PGFREE);
pcp = &this_cpu_ptr(zone->pageset)->pcp;
if (!cold)
list_add(&page->lru, &pcp->lists[migratetype]);
@@ -2529,7 +2527,7 @@
}
out:
- preempt_enable();
+ local_irq_restore(flags);
}
/*
@@ -2654,8 +2652,6 @@
{
struct page *page;
- VM_BUG_ON(in_interrupt());
-
do {
if (list_empty(list)) {
pcp->count += rmqueue_bulk(zone, 0,
@@ -2686,8 +2682,9 @@
struct list_head *list;
bool cold = ((gfp_flags & __GFP_COLD) != 0);
struct page *page;
+ unsigned long flags;
- preempt_disable();
+ local_irq_save(flags);
pcp = &this_cpu_ptr(zone->pageset)->pcp;
list = &pcp->lists[migratetype];
page = __rmqueue_pcplist(zone, migratetype, cold, pcp, list);
@@ -2695,7 +2692,7 @@
__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
zone_statistics(preferred_zone, zone);
}
- preempt_enable();
+ local_irq_restore(flags);
return page;
}
@@ -2711,7 +2708,7 @@
unsigned long flags;
struct page *page;
- if (likely(order == 0) && !in_interrupt()) {
+ if (likely(order == 0)) {
page = rmqueue_pcplist(preferred_zone, zone, order,
gfp_flags, migratetype);
goto out;