thp, vmstat: implement HZP_ALLOC and HZP_ALLOC_FAILED events

[deliverable/linux.git] / Documentation / vm / transhuge.txt

diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
index 8f5b41db314cfe0f9c6e1e978cdfd315ddf26019..60aeedd54615328c00937691685066f9348c0fe5 100644 (file)
--- a/Documentation/vm/transhuge.txt
+++ b/Documentation/vm/transhuge.txt
@@ -197,6 +197,14 @@ thp_split is incremented every time a huge page is split into base
        pages. This can happen for a variety of reasons but a common
        reason is that a huge page is old and is being reclaimed.
 
+thp_zero_page_alloc is incremented every time a huge zero page is
+       successfully allocated. It includes allocations which where
+       dropped due race with other allocation. Note, it doesn't count
+       every map of the huge zero page, only its allocation.
+
+thp_zero_page_alloc_failed is incremented if kernel fails to allocate
+       huge zero page and falls back to using small pages.
+
 As the system ages, allocating huge pages may be expensive as the
 system uses memory compaction to copy data around memory to free a
 huge page for use. There are some counters in /proc/vmstat to help