mm: swap: Count successful large folio zswap stores in hugepage zswpout stats

Added a new MTHP_STAT_ZSWPOUT entry to the sysfs transparent_hugepage
stats so that successful large folio zswap stores can be accounted under
the per-order sysfs "zswpout" stats:

/sys/kernel/mm/transparent_hugepage/hugepages-*kB/stats/zswpout

Other non-zswap swap device swap-out events will be counted under
the existing sysfs "swpout" stats:

/sys/kernel/mm/transparent_hugepage/hugepages-*kB/stats/swpout

Also, added documentation for the newly added sysfs per-order hugepage
"zswpout" stats. The documentation clarifies that only non-zswap swapouts
will be accounted in the existing "swpout" stats.

Link: https://lkml.kernel.org/r/20241001053222.6944-8-kanchana.p.sridhar@intel.com
Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@intel.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Wajdi Feghali <wajdi.k.feghali@intel.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: "Zou, Nanhai" <nanhai.zou@intel.com>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index cfdd16a52e39fdff0a478b44b9ad97726029d674..2a171ed5206e749959a09c42e95f3135d3ebc5c1 100644 (file)
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -530,10 +530,14 @@ anon_fault_fallback_charge
        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 in one
+zswpout
+       is incremented every time a huge page is swapped out to zswap in one
        piece without splitting.
 
+swpout
+       is incremented every time a huge page is swapped out to a non-zswap
+       swap device in one piece without splitting.
+
 swpout_fallback
        is incremented if a huge page has to be split before swapout.
        Usually because failed to allocate some continuous swap space

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 8afe09a2cf03b0531da34eb67497cedf67276e6f..d5f824d5e1c5925bad386b0e0985394ff6cb0320 100644 (file)
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -119,6 +119,7 @@ enum mthp_stat_item {
        MTHP_STAT_ANON_FAULT_ALLOC,
        MTHP_STAT_ANON_FAULT_FALLBACK,
        MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
+       MTHP_STAT_ZSWPOUT,
        MTHP_STAT_SWPOUT,
        MTHP_STAT_SWPOUT_FALLBACK,
        MTHP_STAT_SHMEM_ALLOC,

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e71b58d84cba230e5ba2d609631f04096e39c410..2f24d9cbba5b0530d3efda87682cf91ddafaf5de 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -600,6 +600,7 @@ static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
 DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC);
 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(swpout, MTHP_STAT_SWPOUT);
 DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
 #ifdef CONFIG_SHMEM
@@ -618,6 +619,7 @@ static struct attribute *anon_stats_attrs[] = {
        &anon_fault_fallback_attr.attr,
        &anon_fault_fallback_charge_attr.attr,
 #ifndef CONFIG_SHMEM
+       &zswpout_attr.attr,
        &swpout_attr.attr,
        &swpout_fallback_attr.attr,
 #endif
@@ -648,6 +650,7 @@ static struct attribute_group file_stats_attr_grp = {
 
 static struct attribute *any_stats_attrs[] = {
 #ifdef CONFIG_SHMEM
+       &zswpout_attr.attr,
        &swpout_attr.attr,
        &swpout_fallback_attr.attr,
 #endif

diff --git a/mm/page_io.c b/mm/page_io.c
index 40392782cdcb9d62bac9b29eb28e97735c135147..be6cd314845a33de7caea9d66e58dadd5fabe55c 100644 (file)
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -269,6 +269,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
                swap_zeromap_folio_clear(folio);
        }
        if (zswap_store(folio)) {
+               count_mthp_stat(folio_order(folio), MTHP_STAT_ZSWPOUT);
                folio_unlock(folio);
                return 0;
        }