Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 5 Dec 2018 11:00:19 -0800 (PST)
From:   David Rientjes <rientjes@google.com>
To:     Pingfan Liu <kernelfans@gmail.com>
cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH] mm/alloc: fallback to first node if the wanted node
 offline
In-Reply-To: <CAFgQCTttgfuPJZHqGDSF5hLpLWDm2+_+UiyK+ScKgxs6qD-KCQ@mail.gmail.com>
Message-ID: <alpine.DEB.2.21.1812051058440.240991@chino.kir.corp.google.com>
References: <1543892757-4323-1-git-send-email-kernelfans@gmail.com> <alpine.DEB.2.21.1812031946140.97328@chino.kir.corp.google.com> <CAFgQCTsikqQERh2MgsrupdVzp0TyF4dDQPjJkN9g3DTq4DB9hw@mail.gmail.com>
 <CAFgQCTttgfuPJZHqGDSF5hLpLWDm2+_+UiyK+ScKgxs6qD-KCQ@mail.gmail.com>
User-Agent: Alpine 2.21 (DEB 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, 5 Dec 2018, Pingfan Liu wrote:

> > > And rather than using first_online_node, would next_online_node() work?
> > >
> > What is the gain? Is it for memory pressure on node0?
> >
> Maybe I got your point now.  Do you try to give a cheap assumption on
> nearest neigh of this node?
> 

It's likely better than first_online_node, but probably going to be the 
same based on the node ids that you have reported since the nodemask will 
simply wrap around back to the first node.