Commit d4241a04 authored May 04, 2021 by Miaohe Lin Committed by Linus Torvalds May 05, 2021

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@huawei.com


Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d83e6c8a

fs/hugetlbfs/inode.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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]);
		}