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Message-Id: <20180720071845.17920-9-ying.huang@intel.com>
Date: Fri, 20 Jul 2018 15:18:45 +0800
From: Huang Ying <ying.huang@...el.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Huang Ying <ying.huang@...el.com>,
Michal Hocko <mhocko@...e.com>,
Johannes Weiner <hannes@...xchg.org>,
Shaohua Li <shli@...nel.org>, Hugh Dickins <hughd@...gle.com>,
Minchan Kim <minchan@...nel.org>,
Rik van Riel <riel@...hat.com>,
Dan Williams <dan.j.williams@...el.com>,
Daniel Jordan <daniel.m.jordan@...cle.com>,
Dave Hansen <dave.hansen@...ux.intel.com>
Subject: [PATCH v4 8/8] swap, put_swap_page: Share more between huge/normal code path
In this patch, locking related code is shared between huge/normal code
path in put_swap_page() to reduce code duplication. And `free_entries
== 0` case is merged into more general `free_entries !=
SWAPFILE_CLUSTER` case, because the new locking method makes it easy.
The added lines is same as the removed lines. But the code size is
increased when CONFIG_TRANSPARENT_HUGEPAGE=n.
text data bss dec hex filename
base: 24123 2004 340 26467 6763 mm/swapfile.o
unified: 24485 2004 340 26829 68cd mm/swapfile.o
Dig on step deeper with `size -A mm/swapfile.o` for base and unified
kernel and compare the result, yields,
-.text 17723 0
+.text 17835 0
-.orc_unwind_ip 1380 0
+.orc_unwind_ip 1480 0
-.orc_unwind 2070 0
+.orc_unwind 2220 0
-Total 26686
+Total 27048
The total difference is the same. The text segment difference is much
smaller: 112. More difference comes from the ORC unwinder
segments: (1480 + 2220) - (1380 + 2070) = 250. If the frame pointer
unwinder is used, this costs nothing.
Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@...cle.com>
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Shaohua Li <shli@...nel.org>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Dan Williams <dan.j.williams@...el.com>
---
mm/swapfile.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 402d52ff3e4a..f792fa902249 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1282,8 +1282,8 @@ void put_swap_page(struct page *page, swp_entry_t entry)
if (!si)
return;
+ ci = lock_cluster_or_swap_info(si, offset);
if (size == SWAPFILE_CLUSTER) {
- ci = lock_cluster(si, offset);
VM_BUG_ON(!cluster_is_huge(ci));
map = si->swap_map + offset;
for (i = 0; i < SWAPFILE_CLUSTER; i++) {
@@ -1292,13 +1292,9 @@ void put_swap_page(struct page *page, swp_entry_t entry)
if (val == SWAP_HAS_CACHE)
free_entries++;
}
- if (!free_entries) {
- for (i = 0; i < SWAPFILE_CLUSTER; i++)
- map[i] &= ~SWAP_HAS_CACHE;
- }
cluster_clear_huge(ci);
- unlock_cluster(ci);
if (free_entries == SWAPFILE_CLUSTER) {
+ unlock_cluster_or_swap_info(si, ci);
spin_lock(&si->lock);
ci = lock_cluster(si, offset);
memset(map, 0, SWAPFILE_CLUSTER);
@@ -1309,12 +1305,16 @@ void put_swap_page(struct page *page, swp_entry_t entry)
return;
}
}
- if (size == 1 || free_entries) {
- for (i = 0; i < size; i++, entry.val++) {
- if (!__swap_entry_free(si, entry, SWAP_HAS_CACHE))
- free_swap_slot(entry);
+ for (i = 0; i < size; i++, entry.val++) {
+ if (!__swap_entry_free_locked(si, offset + i, SWAP_HAS_CACHE)) {
+ unlock_cluster_or_swap_info(si, ci);
+ free_swap_slot(entry);
+ if (i == size - 1)
+ return;
+ lock_cluster_or_swap_info(si, offset);
}
}
+ unlock_cluster_or_swap_info(si, ci);
}
#ifdef CONFIG_THP_SWAP
--
2.16.4
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