The patch titled
Subject: mm/hugetlb: avoid calculating fault_mutex_hash in truncate_op case
has been added to the -mm tree. Its filename is
mm-hugetlb-avoid-calculating-fault_mutex_hash-in-truncate_op-case.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-avoid-calculating-fault_mutex_hash-in-truncate_op-case.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-avoid-calculating-fault_mutex_hash-in-truncate_op-case.patch
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/hugetlb: avoid calculating fault_mutex_hash in truncate_op case
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.
Link: https://lkml.kernel.org/r/20210308112809.26107-6-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/hugetlbfs/inode.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/hugetlbfs/inode.c~mm-hugetlb-avoid-calculating-fault_mutex_hash-in-truncate_op-case
+++ a/fs/hugetlbfs/inode.c
@@ -482,10 +482,9 @@ static void remove_inode_hugepages(struc
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(struc
* 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]);
}
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
hugetlb_cgroup-fix-imbalanced-css_get-and-css_put-pair-for-shared-mappings.patch
mm-hugetlb-remove-redundant-reservation-check-condition-in-alloc_huge_page.patch
mm-hugetlb-use-some-helper-functions-to-cleanup-code.patch
mm-hugetlb-optimize-the-surplus-state-transfer-code-in-move_hugetlb_state.patch
hugetlb_cgroup-remove-unnecessary-vm_bug_on_page-in-hugetlb_cgroup_migrate.patch
mm-hugetlb-simplify-the-code-when-alloc_huge_page-failed-in-hugetlb_no_page.patch
mm-hugetlb-avoid-calculating-fault_mutex_hash-in-truncate_op-case.patch
