linux-kernel - Re: [PATCH] mm/show_mem: Optimize si_meminfo

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Message-ID: <Z-RVhrZuybsQj7l0@kernel.org>
Date: Wed, 26 Mar 2025 15:29:10 -0400
From: Mike Rapoport <rppt@...nel.org>
To: Ye Liu <ye.liu@...ux.dev>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Ye Liu <liuye@...inos.cn>
Subject: Re: [PATCH] mm/show_mem: Optimize si_meminfo_node by reducing
 redundant code

On Tue, Mar 25, 2025 at 03:38:03PM +0800, Ye Liu wrote:
> From: Ye Liu <liuye@...inos.cn>
> 
> Refactors the si_meminfo_node() function by reducing redundant code and
> improving readability.
> 
> Moved the calculation of managed_pages inside the existing loop that
> processes pgdat->node_zones, eliminating the need for a separate loop.
> 
> Simplified the logic by removing unnecessary preprocessor conditionals.
> 
> Ensured that both totalram, totalhigh, and other memory statistics are
> consistently set without duplication.
> 
> This change results in cleaner and more efficient code without altering
> functionality.
> 
> Signed-off-by: Ye Liu <liuye@...inos.cn>
> ---
>  mm/show_mem.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/show_mem.c b/mm/show_mem.c
> index 6af13bcd2ab3..ad373b4b6e39 100644
> --- a/mm/show_mem.c
> +++ b/mm/show_mem.c
> @@ -94,26 +94,20 @@ void si_meminfo_node(struct sysinfo *val, int nid)
>  	unsigned long free_highpages = 0;
>  	pg_data_t *pgdat = NODE_DATA(nid);
>  
> -	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
> -		managed_pages += zone_managed_pages(&pgdat->node_zones[zone_type]);
> -	val->totalram = managed_pages;
> -	val->sharedram = node_page_state(pgdat, NR_SHMEM);
> -	val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
> -#ifdef CONFIG_HIGHMEM
>  	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
>  		struct zone *zone = &pgdat->node_zones[zone_type];
> -
> +		managed_pages += zone_managed_pages(zone);

nit: don't remove the empty line after the declaration

>  		if (is_highmem(zone)) {
>  			managed_highpages += zone_managed_pages(zone);

Looks like highmem pages get counted twice, no?

>  			free_highpages += zone_page_state(zone, NR_FREE_PAGES);
>  		}
>  	}
> +
> +	val->totalram = managed_pages;
> +	val->sharedram = node_page_state(pgdat, NR_SHMEM);
> +	val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
>  	val->totalhigh = managed_highpages;
>  	val->freehigh = free_highpages;
> -#else
> -	val->totalhigh = managed_highpages;
> -	val->freehigh = free_highpages;
> -#endif
>  	val->mem_unit = PAGE_SIZE;
>  }
>  #endif
> -- 
> 2.25.1
> 
> 

-- 
Sincerely yours,
Mike.