d527caf22e
This patch reverts5a03b051("thp: use compaction in kswapd for GFP_ATOMIC order > 0") due to reports stating that kswapd CPU usage was higher and IRQs were being disabled more frequently. This was reported at http://www.spinics.net/linux/fedora/alsa-user/msg09885.html. Without this patch applied, CPU usage by kswapd hovers around the 20% mark according to the tester (Arthur Marsh: http://www.spinics.net/linux/fedora/alsa-user/msg09899.html). With this patch applied, it's around 2%. The problem is not related to THP which specifies __GFP_NO_KSWAPD but is triggered by high-order allocations hitting the low watermark for their order and waking kswapd on kernels with CONFIG_COMPACTION set. The most common trigger for this is network cards configured for jumbo frames but it's also possible it'll be triggered by fork-heavy workloads (order-1) and some wireless cards which depend on order-1 allocations. The symptoms for the user will be high CPU usage by kswapd in low-memory situations which could be confused with another writeback problem. While a patch like5a03b051may be reintroduced in the future, this patch plays it safe for now and reverts it. [mel@csn.ul.ie: Beefed up the changelog] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reported-by: Arthur Marsh <arthur.marsh@internode.on.net> Tested-by: Arthur Marsh <arthur.marsh@internode.on.net> Cc: <stable@kernel.org> [2.6.38.1] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
106 lines
3.1 KiB
C
106 lines
3.1 KiB
C
#ifndef _LINUX_COMPACTION_H
|
|
#define _LINUX_COMPACTION_H
|
|
|
|
/* Return values for compact_zone() and try_to_compact_pages() */
|
|
/* compaction didn't start as it was not possible or direct reclaim was more suitable */
|
|
#define COMPACT_SKIPPED 0
|
|
/* compaction should continue to another pageblock */
|
|
#define COMPACT_CONTINUE 1
|
|
/* direct compaction partially compacted a zone and there are suitable pages */
|
|
#define COMPACT_PARTIAL 2
|
|
/* The full zone was compacted */
|
|
#define COMPACT_COMPLETE 3
|
|
|
|
#ifdef CONFIG_COMPACTION
|
|
extern int sysctl_compact_memory;
|
|
extern int sysctl_compaction_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *length, loff_t *ppos);
|
|
extern int sysctl_extfrag_threshold;
|
|
extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *length, loff_t *ppos);
|
|
|
|
extern int fragmentation_index(struct zone *zone, unsigned int order);
|
|
extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
|
|
int order, gfp_t gfp_mask, nodemask_t *mask,
|
|
bool sync);
|
|
extern unsigned long compaction_suitable(struct zone *zone, int order);
|
|
extern unsigned long compact_zone_order(struct zone *zone, int order,
|
|
gfp_t gfp_mask, bool sync);
|
|
|
|
/* Do not skip compaction more than 64 times */
|
|
#define COMPACT_MAX_DEFER_SHIFT 6
|
|
|
|
/*
|
|
* Compaction is deferred when compaction fails to result in a page
|
|
* allocation success. 1 << compact_defer_limit compactions are skipped up
|
|
* to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
|
|
*/
|
|
static inline void defer_compaction(struct zone *zone)
|
|
{
|
|
zone->compact_considered = 0;
|
|
zone->compact_defer_shift++;
|
|
|
|
if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
|
|
zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
|
|
}
|
|
|
|
/* Returns true if compaction should be skipped this time */
|
|
static inline bool compaction_deferred(struct zone *zone)
|
|
{
|
|
unsigned long defer_limit = 1UL << zone->compact_defer_shift;
|
|
|
|
/* Avoid possible overflow */
|
|
if (++zone->compact_considered > defer_limit)
|
|
zone->compact_considered = defer_limit;
|
|
|
|
return zone->compact_considered < (1UL << zone->compact_defer_shift);
|
|
}
|
|
|
|
#else
|
|
static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
|
|
int order, gfp_t gfp_mask, nodemask_t *nodemask,
|
|
bool sync)
|
|
{
|
|
return COMPACT_CONTINUE;
|
|
}
|
|
|
|
static inline unsigned long compaction_suitable(struct zone *zone, int order)
|
|
{
|
|
return COMPACT_SKIPPED;
|
|
}
|
|
|
|
static inline unsigned long compact_zone_order(struct zone *zone, int order,
|
|
gfp_t gfp_mask, bool sync)
|
|
{
|
|
return COMPACT_CONTINUE;
|
|
}
|
|
|
|
static inline void defer_compaction(struct zone *zone)
|
|
{
|
|
}
|
|
|
|
static inline bool compaction_deferred(struct zone *zone)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
#endif /* CONFIG_COMPACTION */
|
|
|
|
#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
|
|
extern int compaction_register_node(struct node *node);
|
|
extern void compaction_unregister_node(struct node *node);
|
|
|
|
#else
|
|
|
|
static inline int compaction_register_node(struct node *node)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline void compaction_unregister_node(struct node *node)
|
|
{
|
|
}
|
|
#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
|
|
|
|
#endif /* _LINUX_COMPACTION_H */
|