linux-kernel - [PATCHv2 2/4] zsmalloc: skip chain size calculation for pow_of

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Message-Id: <20230109033838.2779902-3-senozhatsky@chromium.org>
Date:   Mon,  9 Jan 2023 12:38:36 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCHv2 2/4] 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.

Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 mm/zsmalloc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index effe10fe76e9..ee8431784998 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -2287,6 +2287,9 @@ 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;
 
-- 
2.39.0.314.g84b9a713c41-goog