path: root/mm
diff options
authorHuang Ying <ying.huang@intel.com>2018-08-21 21:52:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 10:52:43 -0700
commit59d98bf3c2b9218ff4cdb2a70aa52fffedf1786c (patch)
treeea5db5462bc320a566e41ca5308e4c65e901587d /mm
parente50ef89b0f58a2cb0e7d496a97b851e0dced62a6 (diff)
mm: swap: add comments to lock_cluster_or_swap_info()
Patch series "swap: THP optimizing refactoring", v4. Now the THP (Transparent Huge Page) swap optimizing is implemented in the way like below, #ifdef CONFIG_THP_SWAP huge_function(...) { } #else normal_function(...) { } #endif general_function(...) { if (huge) return thp_function(...); else return normal_function(...); } As pointed out by Dave Hansen, this will, 1. Create a new, wholly untested code path for huge page 2. Create two places to patch bugs 3. Are not reusing code when possible This patchset is to address these problems via merging huge/normal code path/functions if possible. One concern is that this may cause code size to dilate when !CONFIG_TRANSPARENT_HUGEPAGE. The data shows that most refactoring will only cause quite slight code size increase. This patch (of 8): To improve code readability. Link: http://lkml.kernel.org/r/20180720071845.17920-2-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-and-acked-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shaohua Li <shli@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 7 insertions, 2 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 8837b22c848d..52a9dd9dab8e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -296,13 +296,18 @@ static inline void unlock_cluster(struct swap_cluster_info *ci)
+ * Determine the locking method in use for this device. Return
+ * swap_cluster_info if SSD-style cluster-based locking is in place.
+ */
static inline struct swap_cluster_info *lock_cluster_or_swap_info(
- struct swap_info_struct *si,
- unsigned long offset)
+ struct swap_info_struct *si, unsigned long offset)
struct swap_cluster_info *ci;
+ /* Try to use fine-grained SSD-style locking if available: */
ci = lock_cluster(si, offset);
+ /* Otherwise, fall back to traditional, coarse locking: */
if (!ci)