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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 E2E87C433E1 for ; Thu, 4 Jun 2020 17:45:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 92181204EF for ; Thu, 4 Jun 2020 17:45:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R7g3lf/v" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 92181204EF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0C9C780007; Thu, 4 Jun 2020 13:45:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 07ACD8E0006; Thu, 4 Jun 2020 13:45:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ED24B80007; Thu, 4 Jun 2020 13:45:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0109.hostedemail.com [216.40.44.109]) by kanga.kvack.org (Postfix) with ESMTP id D50178E0006 for ; Thu, 4 Jun 2020 13:45:49 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 9544E1F8690 for ; Thu, 4 Jun 2020 17:45:49 +0000 (UTC) X-FDA: 76892257218.22.birds09_6cd64a30e6956 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 639D9181D378C for ; Thu, 4 Jun 2020 17:45:49 +0000 (UTC) X-HE-Tag: birds09_6cd64a30e6956 X-Filterd-Recvd-Size: 8615 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [207.211.31.81]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Thu, 4 Jun 2020 17:45:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591292747; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=oj+xAGxWNflxShPgkMUsRlyTI7/e09ggt6o5sfkK4cI=; b=R7g3lf/vCgAvjTOUueYXFZACm1B5611OgfqC7mNRNxih0ZLQKgMatcapK9aKMqGobZ+3Jy kolRlHWHrfi45OqixB7EZRAOi/0Q8Ae8ZPBHO6fSDaDdRfzsHr55u40DDegOL6uvzqjY3U K+rZvoVDGGIN9kQ8L587yRRXj7b6ELQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-101-czBYCIaSNAie9hQheAqAIQ-1; Thu, 04 Jun 2020 13:45:45 -0400 X-MC-Unique: czBYCIaSNAie9hQheAqAIQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3A9FF100CCC6; Thu, 4 Jun 2020 17:45:43 +0000 (UTC) Received: from [10.36.112.96] (ovpn-112-96.ams2.redhat.com [10.36.112.96]) by smtp.corp.redhat.com (Postfix) with ESMTP id ED10A7B5EB; Thu, 4 Jun 2020 17:45:40 +0000 (UTC) Subject: Re: [PATCH] x86/mm: use max memory block size with unaligned memory end To: Daniel Jordan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Andy Lutomirski , Dave Hansen , Michal Hocko , Pavel Tatashin , Peter Zijlstra , Steven Sistare References: <20200604035443.3267046-1-daniel.m.jordan@oracle.com> <5827baaf-0eb5-bcea-5d98-727485683512@redhat.com> <20200604172213.f5lufktpqvqjkv4u@ca-dmjordan1.us.oracle.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: Date: Thu, 4 Jun 2020 19:45:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200604172213.f5lufktpqvqjkv4u@ca-dmjordan1.us.oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Rspamd-Queue-Id: 639D9181D378C X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 Content-Transfer-Encoding: quoted-printable 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 04.06.20 19:22, Daniel Jordan wrote: > On Thu, Jun 04, 2020 at 09:22:03AM +0200, David Hildenbrand wrote: >> On 04.06.20 05:54, Daniel Jordan wrote: >>> Some of our servers spend 14 out of the 21 seconds of kernel boot >>> initializing memory block sysfs directories and then creating symlink= s >>> between them and the corresponding nodes. The slowness happens becau= se >>> the machines get stuck with the smallest supported memory block size = on >>> x86 (128M), which results in 16,288 directories to cover the 2T of >>> installed RAM, and each of these paths does a linear search of the >>> memory blocks for every block id, with atomic ops at each step. >> >> With 4fb6eabf1037 ("drivers/base/memory.c: cache memory blocks in xarr= ay >> to accelerate lookup") merged by Linus' today (strange, I thought this >> would be long upstream) >=20 > Ah, thanks for pointing this out! It was only posted to LKML so I miss= ed it. >=20 >> all linear searches should be gone and at least >> the performance observation in this patch no longer applies. >=20 > The performance numbers as stated, that's certainly true, but this patc= h on top > still improves kernel boot by 7%. It's a savings of half a second -- I= 'll take > it. >=20 > IMHO the root cause of this is really the small block size. Building a= cache > on top to avoid iterating over tons of small blocks seems like papering= over > the problem, especially when one of the two affected paths in boot is a The memory block size dictates your memory hot(un)plug granularity. E.g., on powerpc that's 16MB so they have *a lot* of memory blocks. That's why that's not papering over the problem. Increasing the memory block size isn't always the answer. (there are other, still fairly academic approaches to power down memory banks where you also want small memory blocks instead) > cautious check that might be ready to be removed by now[0]: Yeah, we discussed that somewhere already. My change only highlighted the problem. And now that it's cheap, it can just stay unless there is a very good reason not to do it. >=20 > static int init_memory_block(struct memory_block **memory, > unsigned long block_id, unsigned long state) > { > ... > mem =3D find_memory_block_by_id(block_id); > if (mem) { > put_device(&mem->dev); > return -EEXIST; > } >=20 > Anyway, I guess I'll redo the changelog and post again. >=20 >> The memmap init should nowadays consume most time. >=20 > Yeah, but of course it's not as bad as it was now that it's fully paral= lelized. Right. I also observed that computing if a zone is contiguous can be expensive. --=20 Thanks, David / dhildenb