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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id x6si19469967pln.74.2019.04.29.13.10.06 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 29 Apr 2019 13:10:06 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of batv+3f5cf76c63215fb3955b+5727+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b="Bjpos/jn"; spf=pass (google.com: best guess record for domain of batv+3f5cf76c63215fb3955b+5727+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+3f5cf76c63215fb3955b+5727+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=8bbZyLRBS7B6cXqeb9isQNcVt7Ubs7Me5nvL1c8Ic38=; b=Bjpos/jnVGsgKNA3/A6QH5Fqv 3jAKzcTPg0LS0aG86fuHqbtUIILUir1hz6rBxB7r7d76Spl89Z8Gcv+dWrFTZI8otdOJIsCuWdGla IsGgipLBTNfUaQmfJpybjgj5KZPwYQMNLsrgt41VqbtxdI1uyxgXqxQP/r9t7HTkpv2YTFFQFtjFj c2/0WcjJjGr9y26IbUvGg3xsoMGxctAbpUyTmBJ8sWn5pt9/i7RgwGrSJulwzheWOBCwI233+GC5V 1ZhCLQYcffZvx8ZmGnTglQNAETu+5+3vvAuU+/8uDKGmOPm7ZReqSqA9LrrZIJhi2Lo2GoGhgj1Ek g78xqD4+w==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLCb7-0007U6-Fw; Mon, 29 Apr 2019 20:09:57 +0000 Date: Mon, 29 Apr 2019 13:09:57 -0700 From: Christoph Hellwig To: "Luck, Tony" Cc: Christoph Hellwig , Meelis Roos , Christopher Lameter , Mel Gorman , Andrew Morton , Mikulas Patocka , James Bottomley , "linux-parisc@vger.kernel.org" , "linux-mm@kvack.org" , Vlastimil Babka , LKML , "linux-arch@vger.kernel.org" , "Yu, Fenghua" , "linux-ia64@vger.kernel.org" Subject: Re: DISCONTIGMEM is deprecated Message-ID: <20190429200957.GB27158@infradead.org> References: <20190419094335.GJ18914@techsingularity.net> <20190419140521.GI7751@bombadil.infradead.org> <0100016a461809ed-be5bd8fc-9925-424d-9624-4a325a7a8860-000000@email.amazonses.com> <25cabb7c-9602-2e09-2fe0-cad3e54595fa@linux.ee> <20190428081353.GB30901@infradead.org> <3908561D78D1C84285E8C5FCA982C28F7E9140BA@ORSMSX104.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F7E9140BA@ORSMSX104.amr.corp.intel.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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, Apr 29, 2019 at 04:58:09PM +0000, Luck, Tony wrote: > > ia64 has a such a huge number of memory model choices. Maybe we > > need to cut it down to a small set that actually work. > > SGI systems had extremely discontiguous memory (they used some high > order physical address bits in the tens/hundreds of terabyte range for the > node number ... so there would be a few GBytes of actual memory then > a huge gap before the next node had a few more Gbytes). > > I don't know of anyone still booting upstream on an SN2, so if we start doing > serious hack and slash the chances are high that SN2 will be broken (if it isn't > already). When I wrote this, I thought of !NUMA: flat mem NUMA: sparsemem SN2: discontig based on Meelis report. But now that you mention it, I bet SN2 has already died slow death from bitrot. It is so different in places, and it doesn't seem like anyone care - if people want room sized SGI machines the Origin is much more sexy (hello Thomas!) :) So maybe it it time to mark SN2 broken and see if anyone screams? Without SN2 the whole machvec mess could basically go away - the only real difference between the remaining machvecs is which iommu if any we set up.