zsmalloc: skip chain size calculation for pow_of_2 classes

If a class size is power of 2 then it wastes no memory and the best
configuration is 1 physical page per-zspage.

Link: https://lkml.kernel.org/r/20230118005210.2814763-3-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 00ab4cc..7b904f9 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -2370,6 +2370,9 @@ static int calculate_zspage_chain_size(int class_size)
        int i, min_waste = INT_MAX;
        int chain_size = 1;
 
+       if (is_power_of_2(class_size))
+               return chain_size;
+
        for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
                int waste;