+ zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch added to mm-unstable branch

+ zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: zsmalloc: skip chain size calculation for pow_of_2 classes
has been added to the -mm mm-unstable branch.  Its filename is
     zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: zsmalloc: skip chain size calculation for pow_of_2 classes
Date: Mon, 9 Jan 2023 12:38:36 +0900

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/20230109033838.2779902-3-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/zsmalloc.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/zsmalloc.c~zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes
+++ a/mm/zsmalloc.c
@@ -2287,6 +2287,9 @@ static int calculate_zspage_chain_size(i
 	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;
 
_

Patches currently in -mm which might be from senozhatsky@chromium.org are

zram-correctly-handle-all-next_arg-cases.patch
zsmalloc-rework-zspage-chain-size-selection.patch
zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch
zsmalloc-make-zspage-chain-size-configurable.patch
zsmalloc-set-default-zspage-chain-size-to-8.patch

+ zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: zsmalloc: skip chain size calculation for pow_of_2 classes
has been added to the -mm mm-unstable branch.  Its filename is
     zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: zsmalloc: skip chain size calculation for pow_of_2 classes
Date: Wed, 18 Jan 2023 09:52:08 +0900

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>
---


--- a/mm/zsmalloc.c~zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes
+++ a/mm/zsmalloc.c
@@ -2370,6 +2370,9 @@ static int calculate_zspage_chain_size(i
 	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;
 
_

Patches currently in -mm which might be from senozhatsky@chromium.org are

zram-correctly-handle-all-next_arg-cases.patch
zsmalloc-rework-zspage-chain-size-selection.patch
zsmalloc-skip-chain-size-calculation-for-pow_of_2-classes.patch
zsmalloc-make-zspage-chain-size-configurable.patch
zsmalloc-set-default-zspage-chain-size-to-8.patch