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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 4D8C0C433DB for ; Thu, 28 Jan 2021 13:58:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA6D864DD6 for ; Thu, 28 Jan 2021 13:58:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231140AbhA1N6C (ORCPT ); Thu, 28 Jan 2021 08:58:02 -0500 Received: from mx2.suse.de ([195.135.220.15]:48700 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229530AbhA1N55 (ORCPT ); Thu, 28 Jan 2021 08:57:57 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611842231; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=S2RipEAGjkALucqYfiM9qo0yGIYcs4S2Tqn5F8XA884=; b=PqaCl56ujHm2bP9OoWJY3JiPBzBqTsaqdlmuOBE0hZWRpDX9gD/5qfVHMOl0LIRFJFdxDq y3WstcNbzhvD5pWHquB8cBQifeAz4OWnWTlaKNeIhszax3BmvOcxmMjGstg5p5ROw7djeu Fhx+TRURrL/1SJK5jg3OxfEV83g5Saw= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 25E39ABD6; Thu, 28 Jan 2021 13:57:11 +0000 (UTC) Date: Thu, 28 Jan 2021 14:57:10 +0100 From: Michal Hocko To: Mel Gorman Cc: Vincent Guittot , Vlastimil Babka , Christoph Lameter , Bharata B Rao , linux-kernel , linux-mm@kvack.org, David Rientjes , Joonsoo Kim , Andrew Morton , guro@fb.com, Shakeel Butt , Johannes Weiner , aneesh.kumar@linux.ibm.com, Jann Horn Subject: Re: [RFC PATCH v0] mm/slub: Let number of online CPUs determine the slub page order Message-ID: References: <20201118082759.1413056-1-bharata@linux.ibm.com> <20210121053003.GB2587010@in.ibm.com> <20210126085243.GE827@dhcp22.suse.cz> <20210126135918.GQ827@dhcp22.suse.cz> <20210128134512.GF3592@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210128134512.GF3592@techsingularity.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 28-01-21 13:45:12, Mel Gorman wrote: [...] > So mostly this is down to the number of times SLUB calls into the page > allocator which only caches order-0 pages on a per-cpu basis. I do have > a prototype for a high-order per-cpu allocator but it is very rough -- > high watermarks stop making sense, code is rough, memory needed for the > pcpu structures quadruples etc. Thanks this is really useful. But it really begs a question whether this is a general case or more an exception. And as such maybe we want to define high throughput caches which would gain a higher order pages to keep pace with allocation and reduce the churn or deploy some other techniques to reduce the direct page allocator involvement. -- Michal Hocko SUSE Labs