The patch titled
Subject: mm: make transparent hugepage size public
has been added to the -mm tree. Its filename is
mm-make-transparent-hugepage-size-public.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-make-transparent-hugepage-size-public.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-make-transparent-hugepage-size-public.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/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm: make transparent hugepage size public
Test programs want to know the size of a transparent hugepage. While it
is commonly the same as the size of a hugetlbfs page (shown as
Hugepagesize in /proc/meminfo), that is not always so: powerpc implements
transparent hugepages in a different way from hugetlbfs pages, so it's
coincidence when their sizes are the same; and x86 and others can support
more than one hugetlbfs page size.
Add /sys/kernel/mm/transparent_hugepage/hpage_pmd_size to show the THP
size in bytes - it's the same for Anonymous and Shmem hugepages. Call it
hpage_pmd_size (after HPAGE_PMD_SIZE) rather than hpage_size, in case some
transparent support for pud and pgd pages is added later.
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052200290.13021@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/vm/transhuge.txt | 5 +++++
mm/huge_memory.c | 10 ++++++++++
2 files changed, 15 insertions(+)
diff -puN Documentation/vm/transhuge.txt~mm-make-transparent-hugepage-size-public Documentation/vm/transhuge.txt
--- a/Documentation/vm/transhuge.txt~mm-make-transparent-hugepage-size-public
+++ a/Documentation/vm/transhuge.txt
@@ -136,6 +136,11 @@ or enable it back by writing 1:
echo 0 >/sys/kernel/mm/transparent_hugepage/use_zero_page
echo 1 >/sys/kernel/mm/transparent_hugepage/use_zero_page
+Some userspace (such as a test program, or an optimized memory allocation
+library) may want to know the size (in bytes) of a transparent hugepage:
+
+cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
+
khugepaged will be automatically started when
transparent_hugepage/enabled is set to "always" or "madvise, and it'll
be automatically shutdown if it's set to "never".
diff -puN mm/huge_memory.c~mm-make-transparent-hugepage-size-public mm/huge_memory.c
--- a/mm/huge_memory.c~mm-make-transparent-hugepage-size-public
+++ a/mm/huge_memory.c
@@ -285,6 +285,15 @@ static ssize_t use_zero_page_store(struc
}
static struct kobj_attribute use_zero_page_attr =
__ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
+
+static ssize_t hpage_pmd_size_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
+}
+static struct kobj_attribute hpage_pmd_size_attr =
+ __ATTR_RO(hpage_pmd_size);
+
#ifdef CONFIG_DEBUG_VM
static ssize_t debug_cow_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
@@ -307,6 +316,7 @@ static struct attribute *hugepage_attr[]
&enabled_attr.attr,
&defrag_attr.attr,
&use_zero_page_attr.attr,
+ &hpage_pmd_size_attr.attr,
#if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
&shmem_enabled_attr.attr,
#endif
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
mm-add-three-more-cond_resched-in-swapoff.patch
mm-add-cond_resched-in-gather_pte_stats.patch
mm-make-transparent-hugepage-size-public.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
