Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   "Huang, Ying" <ying.huang@intel.com>
To:     liuq <liuq131@chinatelecom.cn>
Cc:     <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mm/min_free_kbytes: modify min_free_kbytes
 calculation rules
References: <20230621073912.21747-1-liuq131@chinatelecom.cn>
Date:   Wed, 21 Jun 2023 15:45:01 +0800
In-Reply-To: <20230621073912.21747-1-liuq131@chinatelecom.cn> (liuq's message
        of "Wed, 21 Jun 2023 15:39:12 +0800")
Message-ID: <87ttv16yyq.fsf@yhuang6-desk2.ccr.corp.intel.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=ascii
Precedence: bulk

Hi, Liuq,

Thanks for updated patch.

liuq <liuq131@chinatelecom.cn> writes:

> The current calculation of min_free_kbytes only uses ZONE_DMA and
> ZONE_NORMAL pages,but the ZONE_MOVABLE zone->_watermark[WMARK_MIN]
> will also divide part of min_free_kbytes.This will cause the min
> watermark of ZONE_NORMAL to be too small in the presence of ZONE_MOVEABLE.
>
> __GFP_HIGH and PF_MEMALLOC allocations usually don't need moveable
> zone pages, so just like ZONE_HIGHMEM, cap pages_min to a small
> value in __setup_per_zone_wmarks.

Please list the test result of your patch.  That is, WMARK_MIN before
and after your patch in a system with large ZONE_MOVABLE.

> Signed-off-by: liuq <liuq131@chinatelecom.cn>
> ---
>  mm/page_alloc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 47421bedc12b..608384712a89 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6364,7 +6364,7 @@ static void __setup_per_zone_wmarks(void)
>  
>  	/* Calculate total number of !ZONE_HIGHMEM pages */
>  	for_each_zone(zone) {
> -		if (!is_highmem(zone))
> +		if (!is_highmem(zone) || zone_idx(zone) != ZONE_MOVABLE)
>  			lowmem_pages += zone_managed_pages(zone);
>  	}
>  
> @@ -6374,7 +6374,7 @@ static void __setup_per_zone_wmarks(void)
>  		spin_lock_irqsave(&zone->lock, flags);
>  		tmp = (u64)pages_min * zone_managed_pages(zone);
>  		do_div(tmp, lowmem_pages);
> -		if (is_highmem(zone)) {
> +		if (is_highmem(zone) || zone_idx(zone) == ZONE_MOVABLE) {
>  			/*
>  			 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
>  			 * need highmem pages, so cap pages_min to a small
                                ~~~~~~~

Change the comments above too?

Best Regards,
Huang, Ying