From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2AFACC433E0 for ; Wed, 10 Mar 2021 15:45:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF9C264FA1 for ; Wed, 10 Mar 2021 15:45:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232405AbhCJPpH (ORCPT ); Wed, 10 Mar 2021 10:45:07 -0500 Received: from mga09.intel.com ([134.134.136.24]:25437 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232523AbhCJPow (ORCPT ); Wed, 10 Mar 2021 10:44:52 -0500 IronPort-SDR: C4+dS4A0x5MMGdxhpgX2JVOf4oYkT2O9KhgvJfkls8C4STjP3PUf35FfLcbKbeABHXV54xIq/C kjnjkIk4Jz/g== X-IronPort-AV: E=McAfee;i="6000,8403,9919"; a="188589510" X-IronPort-AV: E=Sophos;i="5.81,237,1610438400"; d="scan'208";a="188589510" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Mar 2021 07:44:42 -0800 IronPort-SDR: fcQi78U6lYR1iT5VHZvV8wlOLMvaHZ/dua28JgCGxXRVno2xt8kUsdZk9gEMzlRJ1z4Qm+q5jf tFYd8q2xoHCw== X-IronPort-AV: E=Sophos;i="5.81,237,1610438400"; d="scan'208";a="431257138" Received: from umalluga-mobl.amr.corp.intel.com (HELO [10.209.90.191]) ([10.209.90.191]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Mar 2021 07:44:40 -0800 Subject: Re: [PATCH v3 5/5] x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page() To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Dave Hansen , linux-kernel@vger.kernel.org References: <20210303150323.433207-1-jarkko@kernel.org> <20210303150323.433207-6-jarkko@kernel.org> <7621d89e-9347-d8a5-a8b0-a108990d0e6d@intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzShEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gPGRhdmVAc3I3MS5uZXQ+wsF7BBMBAgAlAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAUCTo3k0QIZAQAKCRBoNZUwcMmSsMO2D/421Xg8pimb9mPzM5N7khT0 2MCnaGssU1T59YPE25kYdx2HntwdO0JA27Wn9xx5zYijOe6B21ufrvsyv42auCO85+oFJWfE K2R/IpLle09GDx5tcEmMAHX6KSxpHmGuJmUPibHVbfep2aCh9lKaDqQR07gXXWK5/yU1Dx0r VVFRaHTasp9fZ9AmY4K9/BSA3VkQ8v3OrxNty3OdsrmTTzO91YszpdbjjEFZK53zXy6tUD2d e1i0kBBS6NLAAsqEtneplz88T/v7MpLmpY30N9gQU3QyRC50jJ7LU9RazMjUQY1WohVsR56d ORqFxS8ChhyJs7BI34vQusYHDTp6PnZHUppb9WIzjeWlC7Jc8lSBDlEWodmqQQgp5+6AfhTD kDv1a+W5+ncq+Uo63WHRiCPuyt4di4/0zo28RVcjtzlGBZtmz2EIC3vUfmoZbO/Gn6EKbYAn rzz3iU/JWV8DwQ+sZSGu0HmvYMt6t5SmqWQo/hyHtA7uF5Wxtu1lCgolSQw4t49ZuOyOnQi5 f8R3nE7lpVCSF1TT+h8kMvFPv3VG7KunyjHr3sEptYxQs4VRxqeirSuyBv1TyxT+LdTm6j4a mulOWf+YtFRAgIYyyN5YOepDEBv4LUM8Tz98lZiNMlFyRMNrsLV6Pv6SxhrMxbT6TNVS5D+6 UorTLotDZKp5+M7BTQRUY85qARAAsgMW71BIXRgxjYNCYQ3Xs8k3TfAvQRbHccky50h99TUY sqdULbsb3KhmY29raw1bgmyM0a4DGS1YKN7qazCDsdQlxIJp9t2YYdBKXVRzPCCsfWe1dK/q 66UVhRPP8EGZ4CmFYuPTxqGY+dGRInxCeap/xzbKdvmPm01Iw3YFjAE4PQ4hTMr/H76KoDbD cq62U50oKC83ca/PRRh2QqEqACvIH4BR7jueAZSPEDnzwxvVgzyeuhwqHY05QRK/wsKuhq7s UuYtmN92Fasbxbw2tbVLZfoidklikvZAmotg0dwcFTjSRGEg0Gr3p/xBzJWNavFZZ95Rj7Et db0lCt0HDSY5q4GMR+SrFbH+jzUY/ZqfGdZCBqo0cdPPp58krVgtIGR+ja2Mkva6ah94/oQN lnCOw3udS+Eb/aRcM6detZr7XOngvxsWolBrhwTQFT9D2NH6ryAuvKd6yyAFt3/e7r+HHtkU kOy27D7IpjngqP+b4EumELI/NxPgIqT69PQmo9IZaI/oRaKorYnDaZrMXViqDrFdD37XELwQ gmLoSm2VfbOYY7fap/AhPOgOYOSqg3/Nxcapv71yoBzRRxOc4FxmZ65mn+q3rEM27yRztBW9 AnCKIc66T2i92HqXCw6AgoBJRjBkI3QnEkPgohQkZdAb8o9WGVKpfmZKbYBo4pEAEQEAAcLB XwQYAQIACQUCVGPOagIbDAAKCRBoNZUwcMmSsJeCEACCh7P/aaOLKWQxcnw47p4phIVR6pVL e4IEdR7Jf7ZL00s3vKSNT+nRqdl1ugJx9Ymsp8kXKMk9GSfmZpuMQB9c6io1qZc6nW/3TtvK pNGz7KPPtaDzvKA4S5tfrWPnDr7n15AU5vsIZvgMjU42gkbemkjJwP0B1RkifIK60yQqAAlT YZ14P0dIPdIPIlfEPiAWcg5BtLQU4Wg3cNQdpWrCJ1E3m/RIlXy/2Y3YOVVohfSy+4kvvYU3 lXUdPb04UPw4VWwjcVZPg7cgR7Izion61bGHqVqURgSALt2yvHl7cr68NYoFkzbNsGsye9ft M9ozM23JSgMkRylPSXTeh5JIK9pz2+etco3AfLCKtaRVysjvpysukmWMTrx8QnI5Nn5MOlJj 1Ov4/50JY9pXzgIDVSrgy6LYSMc4vKZ3QfCY7ipLRORyalFDF3j5AGCMRENJjHPD6O7bl3Xo 4DzMID+8eucbXxKiNEbs21IqBZbbKdY1GkcEGTE7AnkA3Y6YB7I/j9mQ3hCgm5muJuhM/2Fr OPsw5tV/LmQ5GXH0JQ/TZXWygyRFyyI2FqNTx4WHqUn3yFj8rwTAU1tluRUYyeLy0ayUlKBH ybj0N71vWO936MqP6haFERzuPAIpxj2ezwu0xb1GjTk4ynna6h5GjnKgdfOWoRtoWndMZxbA z5cecg== Message-ID: Date: Wed, 10 Mar 2021 07:44:39 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> + * node. >>> + */ >>> +static struct sgx_numa_node *sgx_numa_nodes; >>> + >>> +/* >>> + * sgx_free_epc_page() uses this to find out the correct struct sgx_numa_node, >>> + * to put the page in. >>> + */ >>> +static int sgx_section_to_numa_node_id[SGX_MAX_EPC_SECTIONS]; >> >> If this is per-section, why not put it in struct sgx_epc_section? > > Because struct sgx_epc_page does not contain a pointer to > struct sgx_epc_section. Currently, we have epc_page->section. That's not changing. But, with the free list moving from sgx_epc_section to sgx_numa_node, we need a way to get from page->node, not just page->section. We can either add that to: struct sgx_epc_section { ... + struct sgx_numa_node *node; } so we can do epc_page->section->node to find the epc_page's free list, or we could just do: struct sgx_epc_page { - unsigned int section; + unsigned int node; unsigned int flags; struct sgx_encl_page *owner; struct list_head list; struct list_head numa_list; }; and go from page->node directly. >>> page = list_first_entry(&sgx_free_page_list, struct sgx_epc_page, list); >>> + list_del_init(&page->numa_list); >>> list_del_init(&page->list); >>> sgx_nr_free_pages--; >> >> I would much rather prefer that this does what the real page allocator >> does: kep the page on a single list. That list is maintained >> per-NUMA-node. Allocations try local NUMA node structures, then fall >> back to other structures (hopefully in a locality-aware fashion). >> >> I wrote you the loop that I want to see this implement in an earlier >> review. This, basically: >> >> page = NULL; >> nid = numa_node_id(); >> while (true) { >> page = __sgx_alloc_epc_page_from_node(nid); >> if (page) >> break; >> >> nid = // ... some search here, next_node_in()... >> // check if we wrapped around: >> if (nid == numa_node_id()) >> break; >> } >> >> There's no global list. You just walk around nodes trying to find one >> with space. If you wrap around, you stop. >> >> Please implement this. If you think it's a bad idea, or can't, let's >> talk about it in advance. Right now, it appears that my review comments >> aren't being incorporated into newer versions. > > How I interpreted your earlier comments is that the fallback is unfair and > this patch set version does fix that. > > I can buy the above allocation scheme, but I don't think this patch set > version is a step backwards. The things done to struct sgx_epc_section > are exactly what should be done to it. To me, it's a step backwards. It regresses in that it falls back to an entirely non-NUMA aware allocation mechanism. The global list is actually likely to be even worse than the per-section searches because it has a global lock as opposed to the at per-section locks. It also has the overhead of managing two lists instead of one. So, yes, it is *fair* in terms of NUMA node pressure. But being fair in a NUMA-aware allocator by simply not doing NUMA at all is a regression. > Implementation-wise you are asking me to squash 4/5 and 5/5 into a single > patch, and remove global list. It's a tiny iteration from this patch > version and I can do it. Sounds good.