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swap: make each swap partition have one address_space 

When I use several fast SSD to do swap, swapper_space.tree_lock is
heavily contended.  This makes each swap partition have one
address_space to reduce the lock contention.  There is an array of
address_space for swap.  The swap entry type is the index to the array.

In my test with 3 SSD, this increases the swapout throughput 20%.

[akpm@linux-foundation.org: revert unneeded change to  __add_to_swap_cache]
Signed-off-by: Shaohua Li <shli@fusionio.com>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Shaohua Li 2013-02-22 16:34:37 -08:00 committed by Linus Torvalds
parent 9800339b5e
commit 33806f06da
8 changed files with 67 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/proc/meminfo.c
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@ -40,7 +40,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
* sysctl_overcommit_ratio / 100) + total_swap_pages;
cached = global_page_state(NR_FILE_PAGES) -
total_swapcache_pages - i.bufferram;
total_swapcache_pages() - i.bufferram;
if (cached < 0)
cached = 0;
@ -109,7 +109,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
K(i.freeram),
K(i.bufferram),
K(cached),
K(total_swapcache_pages),
K(total_swapcache_pages()),
K(pages[LRU_ACTIVE_ANON] + pages[LRU_ACTIVE_FILE]),
K(pages[LRU_INACTIVE_ANON] + pages[LRU_INACTIVE_FILE]),
K(pages[LRU_ACTIVE_ANON]),

9
include/linux/swap.h
View File

@ -8,7 +8,7 @@
#include <linux/memcontrol.h>
#include <linux/sched.h>
#include <linux/node.h>
#include <linux/fs.h>
#include <linux/atomic.h>
#include <asm/page.h>
@ -330,8 +330,9 @@ int generic_swapfile_activate(struct swap_info_struct *, struct file *,
sector_t *);
/* linux/mm/swap_state.c */
extern struct address_space swapper_space;
#define total_swapcache_pages swapper_space.nrpages
extern struct address_space swapper_spaces[];
#define swap_address_space(entry) (&swapper_spaces[swp_type(entry)])
extern unsigned long total_swapcache_pages(void);
extern void show_swap_cache_info(void);
extern int add_to_swap(struct page *);
extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
@ -382,7 +383,7 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
#define nr_swap_pages 0L
#define total_swap_pages 0L
#define total_swapcache_pages 0UL
#define total_swapcache_pages() 0UL
#define si_swapinfo(val) \
do { (val)->freeswap = (val)->totalswap = 0; } while (0)

4
mm/memcontrol.c
View File

@ -6307,7 +6307,7 @@ static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
* Because lookup_swap_cache() updates some statistics counter,
* we call find_get_page() with swapper_space directly.
*/
page = find_get_page(&swapper_space, ent.val);
page = find_get_page(swap_address_space(ent), ent.val);
if (do_swap_account)
entry->val = ent.val;
@ -6348,7 +6348,7 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
swp_entry_t swap = radix_to_swp_entry(page);
if (do_swap_account)
*entry = swap;
page = find_get_page(&swapper_space, swap.val);
page = find_get_page(swap_address_space(swap), swap.val);
}
#endif
return page;

5
mm/mincore.c
View File

@ -75,7 +75,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
/* shmem/tmpfs may return swap: account for swapcache page too. */
if (radix_tree_exceptional_entry(page)) {
swp_entry_t swap = radix_to_swp_entry(page);
page = find_get_page(&swapper_space, swap.val);
page = find_get_page(swap_address_space(swap), swap.val);
}
#endif
if (page) {
@ -135,7 +135,8 @@ static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
} else {
#ifdef CONFIG_SWAP
pgoff = entry.val;
*vec = mincore_page(&swapper_space, pgoff);
*vec = mincore_page(swap_address_space(entry),
pgoff);
#else
WARN_ON(1);
*vec = 1;

9
mm/swap.c
View File

@ -855,9 +855,14 @@ EXPORT_SYMBOL(pagevec_lookup_tag);
void __init swap_setup(void)
{
unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
#ifdef CONFIG_SWAP
bdi_init(swapper_space.backing_dev_info);
int i;
bdi_init(swapper_spaces[0].backing_dev_info);
for (i = 0; i < MAX_SWAPFILES; i++) {
spin_lock_init(&swapper_spaces[i].tree_lock);
INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
}
#endif
/* Use a smaller cluster for small-memory machines */

55
mm/swap_state.c
View File

@ -36,12 +36,12 @@ static struct backing_dev_info swap_backing_dev_info = {
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
};
struct address_space swapper_space = {
.page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
.tree_lock = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
.a_ops = &swap_aops,
.i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
.backing_dev_info = &swap_backing_dev_info,
struct address_space swapper_spaces[MAX_SWAPFILES] = {
[0 ... MAX_SWAPFILES - 1] = {
.page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
.a_ops = &swap_aops,
.backing_dev_info = &swap_backing_dev_info,
}
};
#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)
@ -53,9 +53,19 @@ static struct {
unsigned long find_total;
} swap_cache_info;
unsigned long total_swapcache_pages(void)
{
int i;
unsigned long ret = 0;
for (i = 0; i < MAX_SWAPFILES; i++)
ret += swapper_spaces[i].nrpages;
return ret;
}
void show_swap_cache_info(void)
{
printk("%lu pages in swap cache\n", total_swapcache_pages);
printk("%lu pages in swap cache\n", total_swapcache_pages());
printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
swap_cache_info.add_total, swap_cache_info.del_total,
swap_cache_info.find_success, swap_cache_info.find_total);
@ -70,6 +80,7 @@ void show_swap_cache_info(void)
static int __add_to_swap_cache(struct page *page, swp_entry_t entry)
{
int error;
struct address_space *address_space;
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(PageSwapCache(page));
@ -79,14 +90,16 @@ static int __add_to_swap_cache(struct page *page, swp_entry_t entry)
SetPageSwapCache(page);
set_page_private(page, entry.val);
spin_lock_irq(&swapper_space.tree_lock);
error = radix_tree_insert(&swapper_space.page_tree, entry.val, page);
address_space = swap_address_space(entry);
spin_lock_irq(&address_space->tree_lock);
error = radix_tree_insert(&address_space->page_tree,
entry.val, page);
if (likely(!error)) {
total_swapcache_pages++;
address_space->nrpages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
INC_CACHE_INFO(add_total);
}
spin_unlock_irq(&swapper_space.tree_lock);
spin_unlock_irq(&address_space->tree_lock);
if (unlikely(error)) {
/*
@ -122,14 +135,19 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
*/
void __delete_from_swap_cache(struct page *page)
{
swp_entry_t entry;
struct address_space *address_space;
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(!PageSwapCache(page));
VM_BUG_ON(PageWriteback(page));
radix_tree_delete(&swapper_space.page_tree, page_private(page));
entry.val = page_private(page);
address_space = swap_address_space(entry);
radix_tree_delete(&address_space->page_tree, page_private(page));
set_page_private(page, 0);
ClearPageSwapCache(page);
total_swapcache_pages--;
address_space->nrpages--;
__dec_zone_page_state(page, NR_FILE_PAGES);
INC_CACHE_INFO(del_total);
}
@ -195,12 +213,14 @@ int add_to_swap(struct page *page)
void delete_from_swap_cache(struct page *page)
{
swp_entry_t entry;
struct address_space *address_space;
entry.val = page_private(page);
spin_lock_irq(&swapper_space.tree_lock);
address_space = swap_address_space(entry);
spin_lock_irq(&address_space->tree_lock);
__delete_from_swap_cache(page);
spin_unlock_irq(&swapper_space.tree_lock);
spin_unlock_irq(&address_space->tree_lock);
swapcache_free(entry, page);
page_cache_release(page);
@ -263,7 +283,7 @@ struct page * lookup_swap_cache(swp_entry_t entry)
{
struct page *page;
page = find_get_page(&swapper_space, entry.val);
page = find_get_page(swap_address_space(entry), entry.val);
if (page)
INC_CACHE_INFO(find_success);
@ -290,7 +310,8 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
* called after lookup_swap_cache() failed, re-calling
* that would confuse statistics.
*/
found_page = find_get_page(&swapper_space, entry.val);
found_page = find_get_page(swap_address_space(entry),
entry.val);
if (found_page)
break;

5
mm/swapfile.c
View File

@ -79,7 +79,7 @@ __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
struct page *page;
int ret = 0;
page = find_get_page(&swapper_space, entry.val);
page = find_get_page(swap_address_space(entry), entry.val);
if (!page)
return 0;
/*
@ -699,7 +699,8 @@ int free_swap_and_cache(swp_entry_t entry)
p = swap_info_get(entry);
if (p) {
if (swap_entry_free(p, entry, 1) == SWAP_HAS_CACHE) {
page = find_get_page(&swapper_space, entry.val);
page = find_get_page(swap_address_space(entry),
entry.val);
if (page && !trylock_page(page)) {
page_cache_release(page);
page = NULL;

10
mm/util.c
View File

@ -6,6 +6,7 @@
#include <linux/sched.h>
#include <linux/security.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <asm/uaccess.h>
#include "internal.h"
@ -389,9 +390,12 @@ struct address_space *page_mapping(struct page *page)
VM_BUG_ON(PageSlab(page));
#ifdef CONFIG_SWAP
if (unlikely(PageSwapCache(page)))
mapping = &swapper_space;
else
if (unlikely(PageSwapCache(page))) {
swp_entry_t entry;
entry.val = page_private(page);
mapping = swap_address_space(entry);
} else
#endif
if ((unsigned long)mapping & PAGE_MAPPING_ANON)
mapping = NULL;