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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 6FE3FC48BE6 for ; Wed, 16 Jun 2021 17:34:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E09E6610A1 for ; Wed, 16 Jun 2021 17:34:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E09E6610A1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7847A6B0036; Wed, 16 Jun 2021 13:34:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 75BE16B006C; Wed, 16 Jun 2021 13:34:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 623F96B0070; Wed, 16 Jun 2021 13:34:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0171.hostedemail.com [216.40.44.171]) by kanga.kvack.org (Postfix) with ESMTP id 32E086B0036 for ; Wed, 16 Jun 2021 13:34:02 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id B2E601263B for ; Wed, 16 Jun 2021 17:34:01 +0000 (UTC) X-FDA: 78260285082.05.95763FD Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf12.hostedemail.com (Postfix) with ESMTP id C3A5C371 for ; Wed, 16 Jun 2021 17:33:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=9gNz19wM+fC67a3J6k98aG2swd11Ci5D+eY1oF5ODtA=; b=bGeItEgi3anUDihg6pqp7DpSGJ VabYcpecBh9yNBuzGEzkH/Pf4InzXEM9+Vcr/Nj0d07n8YxZTTPztgZuPnDSU3xYyKV0UoEkMbBG9 8FvngSXs9xp3PHf42lozhrcjzabobyhRcnviE81rqFKQplPOIw7F0V780HBVP8zUZgVfMd8qvYVwk f0FQnKXxuFjUaQ0l+pDVMpLnf+IYE31tB0zyY0vOJBP4NKTNG+6x3gGvtmzPu2MxIQu4cKOjn/cTQ XQl1Y9yAh7qOmidmqUVqnuRoaPxrbhUY8+lIspdI5yDPg75xAekWuJnezFqQkM2DteNjC4+qRD9lJ IU2mAFkg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1ltZPG-008IwK-7F; Wed, 16 Jun 2021 17:32:58 +0000 Date: Wed, 16 Jun 2021 18:32:50 +0100 From: Matthew Wilcox To: Janghyuck Kim Cc: Catalin Marinas , Will Deacon , Andrew Morton , Palmer Dabbelt , Atish Patra , Gavin Shan , Zhengyuan Liu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] mm: support fastpath if NUMA is enabled with numa off Message-ID: References: <20210616083745.14288-1-janghyuck.kim@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210616083745.14288-1-janghyuck.kim@samsung.com> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C3A5C371 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=bGeItEgi; spf=none (imf12.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Stat-Signature: x64pu394cep7isbee3kfboezrzx83ykp X-HE-Tag: 1623864826-317950 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 Wed, Jun 16, 2021 at 05:37:41PM +0900, Janghyuck Kim wrote: > Architecture might support fake node when CONFIG_NUMA is enabled but any > node settings were supported by ACPI or device tree. In this case, > getting memory policy during memory allocation path is meaningless. > > Moreover, performance degradation was observed in the minor page fault > test, which is provided by (https://lkml.org/lkml/2006/8/29/294). > Average faults/sec of enabling NUMA with fake node was 5~6 % worse than > disabling NUMA. To reduce this performance regression, fastpath is > introduced. fastpath can skip the memory policy checking if NUMA is > enabled but it uses fake node. If architecture doesn't support fake > node, fastpath affects nothing for memory allocation path. This patch doesn't even apply to the current kernel, but putting that aside, what's the expensive part of the current code? That is, comparing performance stats between this numa_off enabled and numa_off disabled, where do you see taking a lot of time?