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[209.85.220.65]) by mx.google.com with SMTPS id y22sor5342585iof.16.2019.02.25.21.40.26 for (Google Transport Security); Mon, 25 Feb 2019 21:40:26 -0800 (PST) Received-SPF: pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Xk3xGW2b; spf=pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=kernelfans@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=bIKVYbyUVD0x9jdnyL5+5v/G/5aUpgYhlC/5rQZY9dI=; b=Xk3xGW2bqs+MwP5/OcRg0YjG9YK6BLHu1KzjWW9S0qmW7NMxGSExR/Kxrg9HIevQ6g kY8uVzwwSOeom37T8+lBvj8V4Cmm1+zqbAUyZ+/L4iFZwCnTCgjNNiY3Gj6v+K+LwFTN wqfnsg6Ab+sDGisUbqN+Aw/FslwU29H4SfDJOnq1sMOnpy3tWwY5U9DRuznQG7exZKss QG3txwqor0aEb6S4xbgJj8ccQ0O/Wdtk/EPN7qnlTMhdBmGbjN799O44fBw/yI+GbrQ8 u+hZcW0iDPfh0wJPdmFOG+wCvIyrv99j71kS+E0xMKOEy1g2d6J91YpHGfjf39+8QD24 Z9sQ== X-Google-Smtp-Source: AHgI3IYmVN0LcCx7sA2wfEjGjxoRPGcF9q1sVEiceCmzWHXRkjjxMmrkI1iTdBUJuPNPILwfnxsyWEMd8bKC6uNA8lc= X-Received: by 2002:a6b:640d:: with SMTP id t13mr5456944iog.102.1551159626677; Mon, 25 Feb 2019 21:40:26 -0800 (PST) MIME-Version: 1.0 References: <1551011649-30103-1-git-send-email-kernelfans@gmail.com> <1551011649-30103-4-git-send-email-kernelfans@gmail.com> <8f703c5f-44c7-3a96-487e-3bdf46ee41b0@intel.com> In-Reply-To: <8f703c5f-44c7-3a96-487e-3bdf46ee41b0@intel.com> From: Pingfan Liu Date: Tue, 26 Feb 2019 13:40:15 +0800 Message-ID: Subject: Re: [PATCH 3/6] x86/numa: define numa_init_array() conditional on CONFIG_NUMA To: Dave Hansen Cc: x86@kernel.org, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Dave Hansen , Vlastimil Babka , Mike Rapoport , Andrew Morton , Mel Gorman , Joonsoo Kim , Andy Lutomirski , Andi Kleen , Petr Tesarik , Michal Hocko , Stephen Rothwell , Jonathan Corbet , Nicholas Piggin , Daniel Vacek , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Feb 25, 2019 at 11:24 PM Dave Hansen wrote: > > On 2/24/19 4:34 AM, Pingfan Liu wrote: > > +#ifdef CONFIG_NUMA > > /* > > * There are unfortunately some poorly designed mainboards around that > > * only connect memory to a single CPU. This breaks the 1:1 cpu->node > > @@ -618,6 +619,9 @@ static void __init numa_init_array(void) > > rr = next_node_in(rr, node_online_map); > > } > > } > > +#else > > +static void __init numa_init_array(void) {} > > +#endif > > What functional effect does this #ifdef have? > > Let's look at the code: > > > static void __init numa_init_array(void) > > { > > int rr, i; > > > > rr = first_node(node_online_map); > > for (i = 0; i < nr_cpu_ids; i++) { > > if (early_cpu_to_node(i) != NUMA_NO_NODE) > > continue; > > numa_set_node(i, rr); > > rr = next_node_in(rr, node_online_map); > > } > > } > > and "play compiler" for a bit. > > The first iteration will see early_cpu_to_node(i)==1 because: > > static inline int early_cpu_to_node(int cpu) > { > return 0; > } > > if CONFIG_NUMA=n. > > In other words, I'm not sure this patch does *anything*. I had thought separating [3/6] and [4/6] can ease the review. And I will merge them in next version. Thanks and regards, Pingfan