The patch titled
Subject: mm/hugetlb: remove unnecessary memory fetch in PageHeadHuge()
has been added to the -mm tree. Its filename is
mm-hugetlb-remove-unnecessary-memory-fetch-in-pageheadhuge.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-remove-unnecessary-memory-fetch-in-pageheadhuge.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-remove-unnecessary-memory-fetch-in-pageheadhuge.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm/hugetlb: remove unnecessary memory fetch in PageHeadHuge()
Commit f1e61557f023 ("mm: pack compound_dtor and compound_order into one
word in struct page") changed compound_dtor from a pointer to an array
index in order to pack it. To check if page has the hugeltbfs
compound_dtor, we can just compare the index directly without fetching the
function pointer. Said commit did that with PageHuge() and we can do the
same with PageHeadHuge() to make the code a bit smaller and faster.
Link: http://lkml.kernel.org/r/20200311172440.6988-1-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Neha Agarwal <nehaagarwal@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/hugetlb.c~mm-hugetlb-remove-unnecessary-memory-fetch-in-pageheadhuge
+++ a/mm/hugetlb.c
@@ -1528,7 +1528,7 @@ int PageHeadHuge(struct page *page_head)
if (!PageHead(page_head))
return 0;
- return get_compound_page_dtor(page_head) == free_huge_page;
+ return page_head[1].compound_dtor == HUGETLB_PAGE_DTOR;
}
/*
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-compaction-fully-assume-capture-is-not-null-in-compact_zone_order.patch
mm-hugetlb-remove-unnecessary-memory-fetch-in-pageheadhuge.patch
