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;
Date:   Wed, 22 Jun 2022 16:54:46 +0800
From:   Muchun Song <songmuchun@bytedance.com>
To:     David Hildenbrand <david@redhat.com>
Cc:     Oscar Salvador <osalvador@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@kernel.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] mm/page_alloc: Do not calculate node's total
 pages and memmap pages when empty
Message-ID: <YrLY1ru0qrvZfqU2@FVFYT0MHHV2J.usts.net>
References: <20220621041717.6355-1-osalvador@suse.de>
 <20220621041717.6355-2-osalvador@suse.de>
 <506203e3-1de0-1187-5234-7afc66d4ddfe@redhat.com>
 <YrKQyhwDwMvueOUc@localhost.localdomain>
 <YrKS6aFHKRyZzAwi@FVFYT0MHHV2J.usts.net>
 <bb71d77e-583a-d216-1aae-2bc062318888@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <bb71d77e-583a-d216-1aae-2bc062318888@redhat.com>
Precedence: bulk

On Wed, Jun 22, 2022 at 10:31:12AM +0200, David Hildenbrand wrote:
> On 22.06.22 05:56, Muchun Song wrote:
> > On Wed, Jun 22, 2022 at 05:47:22AM +0200, Oscar Salvador wrote:
> >> On Tue, Jun 21, 2022 at 09:44:47AM +0200, David Hildenbrand wrote:
> >>>
> >>>
> >>> It's worth noting that the check in pgdat_is_empty() is slightly
> >>> different. I *think* it doesn't matter in practice, yet I wonder if we
> >>> should simply fixup (currently unused) pgdat_is_empty().
> >>
> >> I guess we could change it to
> >>
> >>  static inline bool pgdat_is_empty(pg_data_t *pgdat)
> >>  {
> >> 	 return node_start_pfn(pgdat->node_id) == node_end_pfn(pgdat->node_id)
> >>  }
> >>
> >> ? And maybe even rename it to to node_is_empty (not sure why but I tend to like
> > 
> > At least I like this name (node_is_empty) as well.
> > 
> 
> Let's try keeping it consistent. I think node_is_empty() might indicate
> that we're punching in a node id instead of a pgdat.
>

I suspect Oscar will change the argument to "nid" as well, like:

static inline bool node_is_empty(int nid)
{
	return node_start_pfn(nid) == node_end_pfn(nid);
}

Does this look good?

Thanks.
 
> 
> -- 
> Thanks,
> 
> David / dhildenb
> 
>