Currently, large folio swap-in is supported, but we lack a method to
analyze their success ratio. Similar to anon_fault_fallback, we introduce
per-order mTHP swpin_fallback and swpin_fallback_charge counters for
calculating their success ratio. The new counters are located at:
/sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats/
swpin_fallback
swpin_fallback_charge
Signed-off-by: Wenchao Hao <haowenchao22@xxxxxxxxx>
---
V2:
Introduce swapin_fallback_charge, which increments if it fails to
charge a huge page to memory despite successful allocation.
Documentation/admin-guide/mm/transhuge.rst | 10 ++++++++++
include/linux/huge_mm.h | 2 ++
mm/huge_memory.c | 6 ++++++
mm/memory.c | 2 ++
4 files changed, 20 insertions(+)
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 5034915f4e8e..9c07612281b5 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -561,6 +561,16 @@ swpin
is incremented every time a huge page is swapped in from a non-zswap
swap device in one piece.
+swpin_fallback
+ is incremented if a huge page swapin fails to allocate or charge
+ a huge page and instead falls back to using huge pages with
+ lower orders or small pages.
+
+swpin_fallback_charge
+ is incremented if a page swapin fails to charge a huge page and
+ instead falls back to using huge pages with lower orders or
+ small pages even though the allocation was successful.
+
swpout
is incremented every time a huge page is swapped out to a non-zswap
swap device in one piece without splitting.
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index b94c2e8ee918..93e509b6c00e 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -121,6 +121,8 @@ enum mthp_stat_item {
MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
MTHP_STAT_ZSWPOUT,
MTHP_STAT_SWPIN,
+ MTHP_STAT_SWPIN_FALLBACK,
+ MTHP_STAT_SWPIN_FALLBACK_CHARGE,
MTHP_STAT_SWPOUT,
MTHP_STAT_SWPOUT_FALLBACK,
MTHP_STAT_SHMEM_ALLOC,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ee335d96fc39..46749dded1c9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -617,6 +617,8 @@ DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(zswpout, MTHP_STAT_ZSWPOUT);
DEFINE_MTHP_STAT_ATTR(swpin, MTHP_STAT_SWPIN);
+DEFINE_MTHP_STAT_ATTR(swpin_fallback, MTHP_STAT_SWPIN_FALLBACK);
+DEFINE_MTHP_STAT_ATTR(swpin_fallback_charge, MTHP_STAT_SWPIN_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT);
DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
#ifdef CONFIG_SHMEM
@@ -637,6 +639,8 @@ static struct attribute *anon_stats_attrs[] = {
#ifndef CONFIG_SHMEM
&zswpout_attr.attr,
&swpin_attr.attr,
+ &swpin_fallback_attr.attr,
+ &swpin_fallback_charge_attr.attr,
&swpout_attr.attr,
&swpout_fallback_attr.attr,
#endif
@@ -669,6 +673,8 @@ static struct attribute *any_stats_attrs[] = {
#ifdef CONFIG_SHMEM
&zswpout_attr.attr,
&swpin_attr.attr,
+ &swpin_fallback_attr.attr,
+ &swpin_fallback_charge_attr.attr,
&swpout_attr.attr,
&swpout_fallback_attr.attr,
#endif
diff --git a/mm/memory.c b/mm/memory.c
index 209885a4134f..774dfd309cfe 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4189,8 +4189,10 @@ static struct folio *alloc_swap_folio(struct vm_fault *vmf)
if (!mem_cgroup_swapin_charge_folio(folio, vma->vm_mm,
gfp, entry))
return folio;
+ count_mthp_stat(order, MTHP_STAT_SWPIN_FALLBACK_CHARGE);
folio_put(folio);
}
+ count_mthp_stat(order, MTHP_STAT_SWPIN_FALLBACK);
order = next_order(&orders, order);
}
--
2.45.0
