linux-kernel - RE: [PATCH] mm/compaction: remove unused variable sysctl_compact

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Message-ID: <BYAPR12MB3416C9FD5D10AFB930E1C023D8999@BYAPR12MB3416.namprd12.prod.outlook.com>
Date:   Tue, 2 Mar 2021 20:18:01 +0000
From:   Nitin Gupta <nigupta@...dia.com>
To:     Pintu Kumar <pintu@...eaurora.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "iamjoonsoo.kim@....com" <iamjoonsoo.kim@....com>,
        "sh_def@....com" <sh_def@....com>,
        "mateusznosek0@...il.com" <mateusznosek0@...il.com>,
        "bhe@...hat.com" <bhe@...hat.com>,
        "vbabka@...e.cz" <vbabka@...e.cz>,
        "yzaikin@...gle.com" <yzaikin@...gle.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "mgorman@...hsingularity.net" <mgorman@...hsingularity.net>
CC:     "pintu.ping@...il.com" <pintu.ping@...il.com>
Subject: RE: [PATCH] mm/compaction: remove unused variable
 sysctl_compact_memory



> -----Original Message-----
> From: pintu=codeaurora.org@...codeaurora.org
> <pintu=codeaurora.org@...codeaurora.org> On Behalf Of Pintu Kumar
> Sent: Tuesday, March 2, 2021 9:56 AM
> To: linux-kernel@...r.kernel.org; akpm@...ux-foundation.org; linux-
> mm@...ck.org; linux-fsdevel@...r.kernel.org; pintu@...eaurora.org;
> iamjoonsoo.kim@....com; sh_def@....com; mateusznosek0@...il.com;
> bhe@...hat.com; Nitin Gupta <nigupta@...dia.com>; vbabka@...e.cz;
> yzaikin@...gle.com; keescook@...omium.org; mcgrof@...nel.org;
> mgorman@...hsingularity.net
> Cc: pintu.ping@...il.com
> Subject: [PATCH] mm/compaction: remove unused variable
> sysctl_compact_memory
> 
> External email: Use caution opening links or attachments
> 
> 
> The sysctl_compact_memory is mostly unsed in mm/compaction.c It just acts
> as a place holder for sysctl.
> 
> Thus we can remove it from here and move the declaration directly in
> kernel/sysctl.c itself.
> This will also eliminate the extern declaration from header file.


I prefer keeping the existing pattern of listing all compaction related tunables
together in compaction.h:

	extern int sysctl_compact_memory;
	extern unsigned int sysctl_compaction_proactiveness;
	extern int sysctl_extfrag_threshold;
	extern int sysctl_compact_unevictable_allowed;


> No functionality is broken or changed this way.
> 
> Signed-off-by: Pintu Kumar <pintu@...eaurora.org>
> Signed-off-by: Pintu Agarwal <pintu.ping@...il.com>
> ---
>  include/linux/compaction.h | 1 -
>  kernel/sysctl.c            | 1 +
>  mm/compaction.c            | 3 ---
>  3 files changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/include/linux/compaction.h b/include/linux/compaction.h index
> ed4070e..4221888 100644
> --- a/include/linux/compaction.h
> +++ b/include/linux/compaction.h
> @@ -81,7 +81,6 @@ static inline unsigned long compact_gap(unsigned int
> order)  }
> 
>  #ifdef CONFIG_COMPACTION
> -extern int sysctl_compact_memory;
>  extern unsigned int sysctl_compaction_proactiveness;  extern int
> sysctl_compaction_handler(struct ctl_table *table, int write,
>                         void *buffer, size_t *length, loff_t *ppos); diff --git
> a/kernel/sysctl.c b/kernel/sysctl.c index c9fbdd8..66aff21 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -198,6 +198,7 @@ static int max_sched_tunable_scaling =
> SCHED_TUNABLESCALING_END-1;  #ifdef CONFIG_COMPACTION  static int
> min_extfrag_threshold;  static int max_extfrag_threshold = 1000;
> +static int sysctl_compact_memory;
>  #endif
> 
>  #endif /* CONFIG_SYSCTL */
> diff --git a/mm/compaction.c b/mm/compaction.c index 190ccda..ede2886
> 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -2650,9 +2650,6 @@ static void compact_nodes(void)
>                 compact_node(nid);
>  }
> 
> -/* The written value is actually unused, all memory is compacted */ -int
> sysctl_compact_memory;
> -


Please retain this comment for the tunable.

-Nitin