The patch titled
swapfile: rearrange scan and swap_info
has been added to the -mm tree. Its filename is
swapfile-rearrange-scan-and-swap_info.patch
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------------------------------------------------------
Subject: swapfile: rearrange scan and swap_info
From: Hugh Dickins <hugh@xxxxxxxxxxx>
Before making functional changes, rearrange scan_swap_map() to simplify
subsequent diffs. Actually, there is one functional change in there:
leave cluster_nr negative while scanning for a new cluster - resetting it
early increased the likelihood that when we have difficulty finding a free
cluster, another task may come in and try doing exactly the same - just a
waste of cpu.
Before making functional changes, rearrange struct swap_info_struct
slightly: flags will be needed as an unsigned long (for wait_on_bit), next
is a good int to pair with prio, old_block_size is uninteresting so shift
it to the end.
Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/swap.h | 8 ++--
mm/swapfile.c | 66 ++++++++++++++++++++++-------------------
2 files changed, 41 insertions(+), 33 deletions(-)
diff -puN include/linux/swap.h~swapfile-rearrange-scan-and-swap_info include/linux/swap.h
--- a/include/linux/swap.h~swapfile-rearrange-scan-and-swap_info
+++ a/include/linux/swap.h
@@ -133,14 +133,14 @@ enum {
* The in-memory structure used to track swap areas.
*/
struct swap_info_struct {
- unsigned int flags;
+ unsigned long flags;
int prio; /* swap priority */
+ int next; /* next entry on swap list */
struct file *swap_file;
struct block_device *bdev;
struct list_head extent_list;
struct swap_extent *curr_swap_extent;
- unsigned old_block_size;
- unsigned short * swap_map;
+ unsigned short *swap_map;
unsigned int lowest_bit;
unsigned int highest_bit;
unsigned int cluster_next;
@@ -148,7 +148,7 @@ struct swap_info_struct {
unsigned int pages;
unsigned int max;
unsigned int inuse_pages;
- int next; /* next entry on swap list */
+ unsigned int old_block_size;
};
struct swap_list_t {
diff -puN mm/swapfile.c~swapfile-rearrange-scan-and-swap_info mm/swapfile.c
--- a/mm/swapfile.c~swapfile-rearrange-scan-and-swap_info
+++ a/mm/swapfile.c
@@ -89,7 +89,8 @@ void swap_unplug_io_fn(struct backing_de
static inline unsigned long scan_swap_map(struct swap_info_struct *si)
{
- unsigned long offset, last_in_cluster;
+ unsigned long offset;
+ unsigned long last_in_cluster;
int latency_ration = LATENCY_LIMIT;
/*
@@ -103,10 +104,13 @@ static inline unsigned long scan_swap_ma
*/
si->flags += SWP_SCANNING;
- if (unlikely(!si->cluster_nr)) {
- si->cluster_nr = SWAPFILE_CLUSTER - 1;
- if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER)
- goto lowest;
+ offset = si->cluster_next;
+
+ if (unlikely(!si->cluster_nr--)) {
+ if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) {
+ si->cluster_nr = SWAPFILE_CLUSTER - 1;
+ goto checks;
+ }
spin_unlock(&swap_lock);
offset = si->lowest_bit;
@@ -118,43 +122,47 @@ static inline unsigned long scan_swap_ma
last_in_cluster = offset + SWAPFILE_CLUSTER;
else if (offset == last_in_cluster) {
spin_lock(&swap_lock);
- si->cluster_next = offset-SWAPFILE_CLUSTER+1;
- goto cluster;
+ offset -= SWAPFILE_CLUSTER - 1;
+ si->cluster_next = offset;
+ si->cluster_nr = SWAPFILE_CLUSTER - 1;
+ goto checks;
}
if (unlikely(--latency_ration < 0)) {
cond_resched();
latency_ration = LATENCY_LIMIT;
}
}
+
+ offset = si->lowest_bit;
spin_lock(&swap_lock);
- goto lowest;
+ si->cluster_nr = SWAPFILE_CLUSTER - 1;
}
- si->cluster_nr--;
-cluster:
- offset = si->cluster_next;
- if (offset > si->highest_bit)
-lowest: offset = si->lowest_bit;
-checks: if (!(si->flags & SWP_WRITEOK))
+checks:
+ if (!(si->flags & SWP_WRITEOK))
goto no_page;
if (!si->highest_bit)
goto no_page;
- if (!si->swap_map[offset]) {
- if (offset == si->lowest_bit)
- si->lowest_bit++;
- if (offset == si->highest_bit)
- si->highest_bit--;
- si->inuse_pages++;
- if (si->inuse_pages == si->pages) {
- si->lowest_bit = si->max;
- si->highest_bit = 0;
- }
- si->swap_map[offset] = 1;
- si->cluster_next = offset + 1;
- si->flags -= SWP_SCANNING;
- return offset;
+ if (offset > si->highest_bit)
+ offset = si->lowest_bit;
+ if (si->swap_map[offset])
+ goto scan;
+
+ if (offset == si->lowest_bit)
+ si->lowest_bit++;
+ if (offset == si->highest_bit)
+ si->highest_bit--;
+ si->inuse_pages++;
+ if (si->inuse_pages == si->pages) {
+ si->lowest_bit = si->max;
+ si->highest_bit = 0;
}
+ si->swap_map[offset] = 1;
+ si->cluster_next = offset + 1;
+ si->flags -= SWP_SCANNING;
+ return offset;
+scan:
spin_unlock(&swap_lock);
while (++offset <= si->highest_bit) {
if (!si->swap_map[offset]) {
@@ -167,7 +175,7 @@ checks: if (!(si->flags & SWP_WRITEOK))
}
}
spin_lock(&swap_lock);
- goto lowest;
+ goto checks;
no_page:
si->flags -= SWP_SCANNING;
_
Patches currently in -mm which might be from hugh@xxxxxxxxxxx are
linux-next.patch
mm-dont-mark_page_accessed-in-shmem_fault.patch
mm-apply_to_range-call-pte-function-with-lazy-updates.patch
mm-remove-cgroup_mm_owner_callbacks.patch
mm-remove-aop_writepage_activate.patch
mm-remove-gfp_highuser_pagecache.patch
mm-add-setclearpageswapcache-stubs.patch
mm-replace-some-bug_ons-by-vm_bug_ons.patch
mm-add_active_or_unevictable-into-rmap.patch
mm-make-page_lock_anon_vma-static.patch
mm-further-cleanup-page_add_new_anon_rmap.patch
mm-gup-persist-for-write-permission.patch
mm-wp-lock-page-before-deciding-cow.patch
mm-reuse_swap_page-replaces-can_share_swap_page.patch
mm-try_to_free_swap-replaces-remove_exclusive_swap_page.patch
mm-try_to_unuse-check-removing-right-swap.patch
mm-remove-try_to_munlock-from-vmscan.patch
mm-remove-gfp_mask-from-add_to_swap.patch
mm-add-add_to_swap-stub.patch
mm-optimize-get_scan_ratio-for-no-swap.patch
make-get_user_pages-interruptible.patch
make-get_user_pages-interruptible-update.patch
swapfile-swapon-needs-larger-size-type.patch
swapfile-remove-swp_active-mask.patch
swapfile-remove-surplus-whitespace.patch
swapfile-remove-v0-swap-space-message.patch
swapfile-rearrange-scan-and-swap_info.patch
swapfile-swapon-use-discard-trim.patch
swapfile-swap-allocation-use-discard.patch
swapfile-swapon-randomize-if-nonrot.patch
swapfile-swap-allocation-cycle-if-nonrot.patch
memcg-handle-swap-caches.patch
memcg-handle-swap-caches-build-fix.patch
memcg-swap-cgroup-for-remembering-usage.patch
memcg-memswap-controller-core.patch
memcg-memswap-controller-core-make-resize-limit-hold-mutex.patch
memcg-memswap-controller-core-swapcache-fixes.patch
prio_tree-debugging-patch.patch
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