From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200])
	by kanga.kvack.org (Postfix) with ESMTP id 154106B7D1A
	for <linux-mm@kvack.org>; Thu,  6 Dec 2018 18:38:43 -0500 (EST)
Received: by mail-pf1-f200.google.com with SMTP id t2so1658141pfj.15
        for <linux-mm@kvack.org>; Thu, 06 Dec 2018 15:38:43 -0800 (PST)
Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115])
        by mx.google.com with ESMTPS id i69si1383878pgc.538.2018.12.06.15.38.41
        for <linux-mm@kvack.org>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Thu, 06 Dec 2018 15:38:42 -0800 (PST)
Subject: Re: [RFC PATCH 00/14] Heterogeneous Memory System (HMS) and hbind()
References: <20181205001544.GR2937@redhat.com>
 <42006749-7912-1e97-8ccd-945e82cebdde@intel.com>
 <20181205021334.GB3045@redhat.com>
 <b3122fdf-02c3-2e9c-1da6-fb873b824d59@intel.com>
 <20181205175357.GG3536@redhat.com>
 <b8fab9a7-62ed-5d8d-3cb1-aea6aacf77fe@intel.com>
 <20181206192050.GC3544@redhat.com>
 <d6508932-377c-a4d1-d4d8-01d0f55b9190@intel.com>
 <c583be1b-17db-1ed3-0f5a-bd119edc8bfe@deltatee.com>
 <f7eb9939-d550-706a-946d-acbb7383172e@intel.com>
 <20181206223935.GG3544@redhat.com>
 <c1126d60-95c0-ed34-6314-fcec17ac1c29@intel.com>
 <935fc14d-91f2-bc2a-f8b5-665e4145e148@deltatee.com>
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <5e6c87d5-e4ef-12e7-32bf-c163f7ff58d7@intel.com>
Date: Thu, 6 Dec 2018 15:38:41 -0800
MIME-Version: 1.0
In-Reply-To: <935fc14d-91f2-bc2a-f8b5-665e4145e148@deltatee.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Logan Gunthorpe <logang@deltatee.com>, Jerome Glisse <jglisse@redhat.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org, "Rafael J . Wysocki" <rafael@kernel.org>, Matthew Wilcox <willy@infradead.org>, Ross Zwisler <ross.zwisler@linux.intel.com>, Keith Busch <keith.busch@intel.com>, Dan Williams <dan.j.williams@intel.com>, Haggai Eran <haggaie@mellanox.com>, Balbir Singh <bsingharora@gmail.com>, "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Felix Kuehling <felix.kuehling@amd.com>, Philip Yang <Philip.Yang@amd.com>, =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>, Paul Blinzer <Paul.Blinzer@amd.com>, John Hubbard <jhubbard@nvidia.com>, Ralph Campbell <rcampbell@nvidia.com>, Michal Hocko <mhocko@kernel.org>, Jonathan Cameron <jonathan.cameron@huawei.com>, Mark Hairgrove <mhairgrove@nvidia.com>, Vivek Kini <vkini@nvidia.com>, Mel Gorman <mgorman@techsingularity.net>, Dave Airlie <airlied@redhat.com>, Ben Skeggs <bskeggs@redhat.com>, Andrea Arcangeli <aarcange@redhat.com>, Rik van Riel <riel@surriel.com>, Ben Woodard <woodard@redhat.com>, linux-acpi@vger.kernel.org

On 12/6/18 3:28 PM, Logan Gunthorpe wrote:
> I didn't think this was meant to describe actual real world performance
> between all of the links. If that's the case all of this seems like a
> pipe dream to me.

The HMAT discussions (that I was a part of at least) settled on just
trying to describe what we called "sticker speed".  Nobody had an
expectation that you *really* had to measure everything.

The best we can do for any of these approaches is approximate things.

> You're not *really* going to know bandwidth or latency for any of this
> unless you actually measure it on the system in question.

Yeah, agreed.