[PATCH 3/3] mm: page_counter: drop protection fields from struct page_counter

[linuszeng via B4 Relay]

From: linuszeng <linusz...@tencent.com>

The protection state now lives in struct page_counter_protection, so
remove the emin/min_usage/children_min_usage, elow/low_usage/
children_low_usage, min, low and protection_support fields from struct
page_counter.

swap/memsw, kmem, tcpmem and hugetlb counters no longer carry this
unused state: on 64-bit the structure shrinks from three cache lines to
two, saving one cache line.
---
 include/linux/page_counter.h | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
index b81f16702764..a4dd461523af 100644
--- a/include/linux/page_counter.h
+++ b/include/linux/page_counter.h
@@ -43,27 +43,11 @@ struct page_counter {
 
        CACHELINE_PADDING(_pad1_);
 
-       /* effective memory.min and memory.min usage tracking */
-       unsigned long emin;
-       atomic_long_t min_usage;
-       atomic_long_t children_min_usage;
-
-       /* effective memory.low and memory.low usage tracking */
-       unsigned long elow;
-       atomic_long_t low_usage;
-       atomic_long_t children_low_usage;
-
        unsigned long watermark;
        /* Latest cg2 reset watermark */
        unsigned long local_watermark;
 
-       /* Keep all the read most fields in a separete cacheline. */
-       CACHELINE_PADDING(_pad2_);
-
-       bool protection_support;
        bool track_failcnt;
-       unsigned long min;
-       unsigned long low;
        unsigned long high;
        unsigned long max;
        struct page_counter *parent;
@@ -73,6 +57,9 @@ struct page_counter {
         * support memory.min/memory.low (swap, memsw, kmem, tcpmem, ...).
         */
        struct page_counter_protection *prot;
+
+       /* Keep all the read most fields in a separete cacheline. */
+       CACHELINE_PADDING(_pad2_);
 } ____cacheline_internodealigned_in_smp;
 
 #if BITS_PER_LONG == 32

-- 
2.43.7