On 2024/4/23 19:39, Ryan Roberts wrote:
On 23/04/2024 02:46, Baolin Wang wrote:
On 2024/4/23 09:17, Barry Song wrote:
On Mon, Apr 22, 2024 at 3:03 PM Baolin Wang
<baolin.wang@xxxxxxxxxxxxxxxxx> wrote:
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
include/linux/huge_mm.h | 2 ++
mm/huge_memory.c | 4 ++++
mm/shmem.c | 5 ++++-
3 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 26b6fa98d8ac..67b9c1acad31 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -270,6 +270,8 @@ enum mthp_stat_item {
MTHP_STAT_ANON_SWPOUT,
MTHP_STAT_ANON_SWPOUT_FALLBACK,
MTHP_STAT_ANON_SWPIN_REFAULT,
+ MTHP_STAT_SHMEM_ANON_ALLOC,
+ MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK,
not quite sure about this. for 2MB pmd-mapped THP shmem, we count them
as FILE_THP.
here we are counting as SHMEM_ANON. To me, SHMEM_ANON is more correct but
it doesn't align with pmd-mapped THP. David, Ryan, what do you think?
Thanks for reviewing.
IMO, I think both approaches are acceptable, which also reflects the dual nature
of anonymous shared pages: on the one hand they are anonymous pages, and on the
other hand, they are backed by a pseudo file. From the user's perspective, I
prefer to use the term "anonymous shmem", which can be distinguished from the
real file-backed THP.
Anyway, let's see what others think.
From a quick look at the code, it looks like the shmem alloc/fallback/charge
events are all lumped in with FILE_THP. But the instantaneous "how many are
allocated" and "how many are mapped" have their own NR_SHMEM_THPS and
NR_SHMEM_PMDMAPPED counters? So its a bit inconsistent today.
My preference would be to add these to be consistent with the anon stats:
MTHP_STAT_SHMEM_FAULT_ALLOC,
MTHP_STAT_SHMEM_FAULT_FALLBACK,
MTHP_STAT_SHMEM_FAULT_FALLBACK_CHARGE,
But it looks like these aren't always allocated due to faults? So perhaps:
MTHP_STAT_SHMEM_ALLOC,
MTHP_STAT_SHMEM_FALLBACK,
MTHP_STAT_SHMEM_FALLBACK_CHARGE,
This looks good to me.
If I've understood the code correctly (I know nothing about shmem), the
allocation can be for both mmap(SHARED|ANON) and for tmpfs? So "SHMEM_ANON"
This is allowed, but the 'fd' for tmpfs will be ignored (see
ksys_mmap_pgoff()), which is same with anonymous shmem.
probably isn't quite right?
__MTHP_STAT_COUNT
};
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9e52c0db7580..dc15240c1ab3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -557,6 +557,8 @@ DEFINE_MTHP_STAT_ATTR(anon_alloc_fallback,
MTHP_STAT_ANON_ALLOC_FALLBACK);
DEFINE_MTHP_STAT_ATTR(anon_swpout, MTHP_STAT_ANON_SWPOUT);
DEFINE_MTHP_STAT_ATTR(anon_swpout_fallback, MTHP_STAT_ANON_SWPOUT_FALLBACK);
DEFINE_MTHP_STAT_ATTR(anon_swpin_refault, MTHP_STAT_ANON_SWPIN_REFAULT);
+DEFINE_MTHP_STAT_ATTR(shmem_anon_alloc, MTHP_STAT_SHMEM_ANON_ALLOC);
+DEFINE_MTHP_STAT_ATTR(shmem_anon_alloc_fallback,
MTHP_STAT_SHMEM_ANON_ALLOC_FALLBACK);
static struct attribute *stats_attrs[] = {
&anon_alloc_attr.attr,
@@ -564,6 +566,8 @@ static struct attribute *stats_attrs[] = {
&anon_swpout_attr.attr,
&anon_swpout_fallback_attr.attr,
&anon_swpin_refault_attr.attr,
+ &shmem_anon_alloc_attr.attr,
+ &shmem_anon_alloc_fallback_attr.attr,
NULL,
};
diff --git a/mm/shmem.c b/mm/shmem.c
index 8b009e7040b2..4a0aa75ab29c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1706,11 +1706,14 @@ static struct folio *shmem_alloc_and_add_folio(struct
vm_fault *vmf,
pages = 1 << order;
index = round_down(index, pages);
folio = shmem_alloc_hugefolio(gfp, info, index, order);
- if (folio)
+ if (folio) {
+ count_mthp_stat(order,
MTHP_STAT_SHMEM_ANON_ALLOC);
is there any reason why this can't go next to the existing PMD-size stat?
No, will move to the existing PMD-size stat.
