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authorTim Chen <tim.c.chen@linux.intel.com>2017-02-23 02:45:39 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-23 03:41:30 +0300
commit67afa38e012e9581b9b42f2a41dfc56b1280794d (patch)
tree704ee023982fdcdc053c4950e26656888ca289f5 /mm/swapfile.c
parent7c00bafee87c7bac7ed9eced7c161f8e5332cb4e (diff)
downloadlinux-67afa38e012e9581b9b42f2a41dfc56b1280794d.tar.xz
mm/swap: add cache for swap slots allocation
We add per cpu caches for swap slots that can be allocated and freed quickly without the need to touch the swap info lock. Two separate caches are maintained for swap slots allocated and swap slots returned. This is to allow the swap slots to be returned to the global pool in a batch so they will have a chance to be coaelesced with other slots in a cluster. We do not reuse the slots that are returned right away, as it may increase fragmentation of the slots. The swap allocation cache is protected by a mutex as we may sleep when searching for empty slots in cache. The swap free cache is protected by a spin lock as we cannot sleep in the free path. We refill the swap slots cache when we run out of slots, and we disable the swap slots cache and drain the slots if the global number of slots fall below a low watermark threshold. We re-enable the cache agian when the slots available are above a high watermark. [ying.huang@intel.com: use raw_cpu_ptr over this_cpu_ptr for swap slots access] [tim.c.chen@linux.intel.com: add comments on locks in swap_slots.h] Link: http://lkml.kernel.org/r/20170118180327.GA24225@linux.intel.com Link: http://lkml.kernel.org/r/35de301a4eaa8daa2977de6e987f2c154385eb66.1484082593.git.tim.c.chen@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Michal Hocko <mhocko@suse.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> escreveu: Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c26
1 files changed, 15 insertions, 11 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 8b5bd34b1a00..30a90fd140b7 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -34,6 +34,7 @@
#include <linux/frontswap.h>
#include <linux/swapfile.h>
#include <linux/export.h>
+#include <linux/swap_slots.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
@@ -854,14 +855,6 @@ noswap:
return n_ret;
}
-swp_entry_t get_swap_page(void)
-{
- swp_entry_t entry;
-
- get_swap_pages(1, &entry);
- return entry;
-}
-
/* The only caller of this function is now suspend routine */
swp_entry_t get_swap_page_of_type(int type)
{
@@ -1052,7 +1045,7 @@ void swap_free(swp_entry_t entry)
p = _swap_info_get(entry);
if (p) {
if (!__swap_entry_free(p, entry, 1))
- swapcache_free_entries(&entry, 1);
+ free_swap_slot(entry);
}
}
@@ -1066,7 +1059,7 @@ void swapcache_free(swp_entry_t entry)
p = _swap_info_get(entry);
if (p) {
if (!__swap_entry_free(p, entry, SWAP_HAS_CACHE))
- swapcache_free_entries(&entry, 1);
+ free_swap_slot(entry);
}
}
@@ -1288,7 +1281,7 @@ int free_swap_and_cache(swp_entry_t entry)
page = NULL;
}
} else if (!count)
- swapcache_free_entries(&entry, 1);
+ free_swap_slot(entry);
}
if (page) {
/*
@@ -2116,6 +2109,17 @@ static void reinsert_swap_info(struct swap_info_struct *p)
spin_unlock(&swap_lock);
}
+bool has_usable_swap(void)
+{
+ bool ret = true;
+
+ spin_lock(&swap_lock);
+ if (plist_head_empty(&swap_active_head))
+ ret = false;
+ spin_unlock(&swap_lock);
+ return ret;
+}
+
SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
{
struct swap_info_struct *p = NULL;