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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 42A6FC433E0 for ; Tue, 16 Mar 2021 09:10:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 008876500B for ; Tue, 16 Mar 2021 09:10:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231404AbhCPJIi (ORCPT ); Tue, 16 Mar 2021 05:08:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:56938 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229717AbhCPJIU (ORCPT ); Tue, 16 Mar 2021 05:08:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615885699; 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; bh=idVxam08guerYh+UThY49AnOxjbt8HD2ng1AgsclHwY=; b=CTxtvsAOm+Aqn8zO1ftigNlJdA960cgB6PUZu6SKwmKn9G5s0fYt6HrFfkHbBy/G9Y8SUZ eOCnQT0FtttCr55xrZ+5n9cX7HX3zU3cJ87l+mPFrpykRo4Y3PwZuzqHKoyYCna8ol05YE v8G5gVh3G30QqtKgCpZ2KzITa1Gq48Y= 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-495-GmrAuuLsOJOt73oh5waFgw-1; Tue, 16 Mar 2021 05:08:16 -0400 X-MC-Unique: GmrAuuLsOJOt73oh5waFgw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 30D2A1084D68; Tue, 16 Mar 2021 09:08:14 +0000 (UTC) Received: from [10.36.114.203] (ovpn-114-203.ams2.redhat.com [10.36.114.203]) by smtp.corp.redhat.com (Postfix) with ESMTP id E34D21F453; Tue, 16 Mar 2021 09:08:11 +0000 (UTC) To: "Liang, Liang (Leo)" , Mike Rapoport Cc: "Deucher, Alexander" , "linux-kernel@vger.kernel.org" , amd-gfx list , Andrew Morton , "Huang, Ray" , "Koenig, Christian" , "Rafael J. Wysocki" , George Kennedy References: <0AE49D98-171A-42B9-9CFC-9193A9BD3346@redhat.com> <22437770-956e-f7b4-a8f6-3f1cc28c3ec2@redhat.com> <0cc972a1-5b40-3017-33f8-b2610489ee18@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Subject: Re: slow boot with 7fef431be9c9 ("mm/page_alloc: place pages to tail in __free_pages_core()") Message-ID: <9e869214-7a3b-e86d-4832-7117f7c6090f@redhat.com> Date: Tue, 16 Mar 2021 10:08:10 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.03.21 09:58, Liang, Liang (Leo) wrote: > [AMD Public Use] > > Hi David, > > root@scbu-Chachani:~# cat /proc/mtrr > reg00: base=0x000000000 ( 0MB), size= 2048MB, count=1: write-back > reg01: base=0x0ffe00000 ( 4094MB), size= 2MB, count=1: write-protect > reg02: base=0x100000000 ( 4096MB), size= 16MB, count=1: write-protect ^ there it is https://wiki.osdev.org/MTRR "Reads allocate cache lines on a cache miss. All writes update main memory. Cache lines are not allocated on a write miss. Write hits invalidate the cache line and update main memory. " AFAIU, writes completely bypass caches and store directly to main mamory. If there are cache lines from a previous read, they are invalidated. So I think especially slow will be read(addr), write(addr), read(addr), ... which is what we have in the kstream benchmark. The question is: who sets this up without owning the memory? Is the memory actually special/slow or is that setting wrong? Buggy firmware/BIOS? Buggy device driver? > reg03: base=0x0ffde0000 ( 4093MB), size= 128KB, count=1: write-protect > reg04: base=0x0ff000000 ( 4080MB), size= 512KB, count=1: write-protect -- Thanks, David / dhildenb