The fault_mutex hashing overhead can be avoided in truncate_op case
because page faults can not race with truncation in this routine. So
calculate hash for fault_mutex only in !truncate_op case to save some cpu
cycles.
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
v2->v3:
keep the initialization in case compilers produce a warning.
Sorry for make noise. :(
v1->v2:
remove unnecessary initialization for variable hash
collect Reviewed-by tag from Mike Kravetz
---
fs/hugetlbfs/inode.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index c262566f7c5d..d81f52b87bd7 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -482,10 +482,9 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
for (i = 0; i < pagevec_count(&pvec); ++i) {
struct page *page = pvec.pages[i];
- u32 hash;
+ u32 hash = 0;
index = page->index;
- hash = hugetlb_fault_mutex_hash(mapping, index);
if (!truncate_op) {
/*
* Only need to hold the fault mutex in the
@@ -493,6 +492,7 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
* page faults. Races are not possible in the
* case of truncation.
*/
+ hash = hugetlb_fault_mutex_hash(mapping, index);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
}
--
2.19.1
