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

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Message-ID: <Z-cqMYag8kzS0MEt@kernel.org>
Date: Sat, 29 Mar 2025 02:01:05 +0300
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

Please don't send html emails to the Linux kernel mailing lists.

On Thu, Mar 27, 2025 at 05:32:14PM +0800, Ye Liu wrote:
> 
> 在 2025/3/27 03:29, Mike Rapoport 写道:
> 
>     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
> 
> Agree.
> 
>                         if (is_highmem(zone)) {
>                                 managed_highpages += zone_managed_pages(zone);
> 
>     Looks like highmem pages get counted twice, no?
> 
> twice? The original logic has not been changed.
> 
> managed_highpages is just high memory, managed_pages is all.

You are right, I misread the patch. 

Feel free to add

Acked-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
 
> Thanks,
> 
> Ye Liu
> 
> 
> 
>                                 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.