The patch titled
Subject: mm: shmem: rename mTHP shmem counters
has been added to the -mm mm-unstable branch. Its filename is
mm-shmem-rename-mthp-shmem-counters.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-rename-mthp-shmem-counters.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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 via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Ryan Roberts <ryan.roberts@xxxxxxx>
Subject: mm: shmem: rename mTHP shmem counters
Date: Wed, 10 Jul 2024 10:55:01 +0100
The legacy PMD-sized THP counters at /proc/vmstat include thp_file_alloc,
thp_file_fallback and thp_file_fallback_charge, which rather confusingly
refer to shmem THP and do not include any other types of file pages. This
is inconsistent since in most other places in the kernel, THP counters are
explicitly separated for anon, shmem and file flavours. However, we are
stuck with it since it constitutes a user ABI.
Recently, commit 66f44583f9b6 ("mm: shmem: add mTHP counters for anonymous
shmem") added equivalent mTHP stats for shmem, keeping the same "file_"
prefix in the names. But in future, we may want to add extra stats to
cover actual file pages, at which point, it would all become very
confusing.
So let's take the opportunity to rename these new counters "shmem_" before
the change makes it upstream and the ABI becomes immutable. While we are
at it, let's improve the documentation for the legacy counters to make it
clear that they count shmem pages only.
Link: https://lkml.kernel.org/r/20240710095503.3193901-1-ryan.roberts@xxxxxxx
Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Reviewed-by: Lance Yang <ioworker0@xxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Barry Song <baohua@xxxxxxxxxx>
Cc: Daniel Gomez <da.gomez@xxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/mm/transhuge.rst | 29 ++++++++++---------
include/linux/huge_mm.h | 6 +--
mm/huge_memory.c | 12 +++----
mm/shmem.c | 8 ++---
4 files changed, 29 insertions(+), 26 deletions(-)
--- a/Documentation/admin-guide/mm/transhuge.rst~mm-shmem-rename-mthp-shmem-counters
+++ a/Documentation/admin-guide/mm/transhuge.rst
@@ -412,20 +412,23 @@ thp_collapse_alloc_failed
the allocation.
thp_file_alloc
- is incremented every time a file huge page is successfully
- allocated.
+ is incremented every time a shmem huge page is successfully
+ allocated (Note that despite being named after "file", the counter
+ measures only shmem).
thp_file_fallback
- is incremented if a file huge page is attempted to be allocated
- but fails and instead falls back to using small pages.
+ is incremented if a shmem huge page is attempted to be allocated
+ but fails and instead falls back to using small pages. (Note that
+ despite being named after "file", the counter measures only shmem).
thp_file_fallback_charge
- is incremented if a file huge page cannot be charged and instead
+ is incremented if a shmem huge page cannot be charged and instead
falls back to using small pages even though the allocation was
- successful.
+ successful. (Note that despite being named after "file", the
+ counter measures only shmem).
thp_file_mapped
- is incremented every time a file huge page is mapped into
+ is incremented every time a file or shmem huge page is mapped into
user address space.
thp_split_page
@@ -496,16 +499,16 @@ swpout_fallback
Usually because failed to allocate some continuous swap space
for the huge page.
-file_alloc
- is incremented every time a file huge page is successfully
+shmem_alloc
+ is incremented every time a shmem huge page is successfully
allocated.
-file_fallback
- is incremented if a file huge page is attempted to be allocated
+shmem_fallback
+ is incremented if a shmem huge page is attempted to be allocated
but fails and instead falls back to using small pages.
-file_fallback_charge
- is incremented if a file huge page cannot be charged and instead
+shmem_fallback_charge
+ is incremented if a shmem huge page cannot be charged and instead
falls back to using small pages even though the allocation was
successful.
--- a/include/linux/huge_mm.h~mm-shmem-rename-mthp-shmem-counters
+++ a/include/linux/huge_mm.h
@@ -269,9 +269,9 @@ enum mthp_stat_item {
MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
MTHP_STAT_SWPOUT,
MTHP_STAT_SWPOUT_FALLBACK,
- MTHP_STAT_FILE_ALLOC,
- MTHP_STAT_FILE_FALLBACK,
- MTHP_STAT_FILE_FALLBACK_CHARGE,
+ MTHP_STAT_SHMEM_ALLOC,
+ MTHP_STAT_SHMEM_FALLBACK,
+ MTHP_STAT_SHMEM_FALLBACK_CHARGE,
MTHP_STAT_SPLIT,
MTHP_STAT_SPLIT_FAILED,
MTHP_STAT_SPLIT_DEFERRED,
--- a/mm/huge_memory.c~mm-shmem-rename-mthp-shmem-counters
+++ a/mm/huge_memory.c
@@ -568,9 +568,9 @@ DEFINE_MTHP_STAT_ATTR(anon_fault_fallbac
DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT);
DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
-DEFINE_MTHP_STAT_ATTR(file_alloc, MTHP_STAT_FILE_ALLOC);
-DEFINE_MTHP_STAT_ATTR(file_fallback, MTHP_STAT_FILE_FALLBACK);
-DEFINE_MTHP_STAT_ATTR(file_fallback_charge, MTHP_STAT_FILE_FALLBACK_CHARGE);
+DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC);
+DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK);
+DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT);
DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
@@ -581,9 +581,9 @@ static struct attribute *stats_attrs[] =
&anon_fault_fallback_charge_attr.attr,
&swpout_attr.attr,
&swpout_fallback_attr.attr,
- &file_alloc_attr.attr,
- &file_fallback_attr.attr,
- &file_fallback_charge_attr.attr,
+ &shmem_alloc_attr.attr,
+ &shmem_fallback_attr.attr,
+ &shmem_fallback_charge_attr.attr,
&split_attr.attr,
&split_failed_attr.attr,
&split_deferred_attr.attr,
--- a/mm/shmem.c~mm-shmem-rename-mthp-shmem-counters
+++ a/mm/shmem.c
@@ -1777,7 +1777,7 @@ static struct folio *shmem_alloc_and_add
if (pages == HPAGE_PMD_NR)
count_vm_event(THP_FILE_FALLBACK);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- count_mthp_stat(order, MTHP_STAT_FILE_FALLBACK);
+ count_mthp_stat(order, MTHP_STAT_SHMEM_FALLBACK);
#endif
order = next_order(&suitable_orders, order);
}
@@ -1804,8 +1804,8 @@ allocated:
count_vm_event(THP_FILE_FALLBACK_CHARGE);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_FALLBACK);
- count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_FALLBACK_CHARGE);
+ count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK);
+ count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK_CHARGE);
#endif
}
goto unlock;
@@ -2181,7 +2181,7 @@ repeat:
if (folio_test_pmd_mappable(folio))
count_vm_event(THP_FILE_ALLOC);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_ALLOC);
+ count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_ALLOC);
#endif
goto alloced;
}
_
Patches currently in -mm which might be from ryan.roberts@xxxxxxx are
mm-fix-khugepaged-activation-policy.patch
mm-fix-khugepaged-activation-policy-v3.patch
mm-shmem-rename-mthp-shmem-counters.patch
