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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 95618C433E4 for ; Tue, 18 Aug 2020 10:26:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 723C020786 for ; Tue, 18 Aug 2020 10:26:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="j7wyfdQz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726632AbgHRK0a (ORCPT ); Tue, 18 Aug 2020 06:26:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726043AbgHRK03 (ORCPT ); Tue, 18 Aug 2020 06:26:29 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 20F43C061389; Tue, 18 Aug 2020 03:26:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=VCX6Iv8QocyVcCbIivzpSCWISFs79AnDnWaSLIjrF8U=; b=j7wyfdQzzEZMB+e5Nys0bXVBDM vXxWFcYB/mrjbGXoK6s/YyXkyE6PEiHxe/nBfggrXwCHEBYZoA+0zTm5Vb1AstfB31VWdqkUhz+Lu GhuVveE3fX33vy9iOUGmUOGQTpcnGX8Le2X92V55OQNMd6LaHzwBqsrrTz20Loi9qbnaDar3Egck5 ZPIiaa51a22YyQbTto8qWi2dofwWO9ePhTZU9EQfrLwzHhf1SZ7eMIaQETjafCmtTZEowmxaz8kI+ BRM4AOz+8lAiFZuTvd6ErYylKdURKpdwxPyyZ4ER3Pkd/KKNdee92nG2DliqRsgvFcnLS+HFsElKf m1hCpYeQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1k7yos-0004EG-CM; Tue, 18 Aug 2020 10:26:18 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 09548300DB4; Tue, 18 Aug 2020 12:26:17 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E60632B76E7C6; Tue, 18 Aug 2020 12:26:16 +0200 (CEST) Date: Tue, 18 Aug 2020 12:26:16 +0200 From: peterz@infradead.org To: Chris Down Cc: Michal Hocko , Waiman Long , Andrew Morton , Johannes Weiner , Vladimir Davydov , Jonathan Corbet , Alexey Dobriyan , Ingo Molnar , Juri Lelli , Vincent Guittot , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control Message-ID: <20200818102616.GP2674@hirez.programming.kicks-ass.net> References: <20200817140831.30260-1-longman@redhat.com> <20200818091453.GL2674@hirez.programming.kicks-ass.net> <20200818092617.GN28270@dhcp22.suse.cz> <20200818095910.GM2674@hirez.programming.kicks-ass.net> <20200818101756.GA155582@chrisdown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200818101756.GA155582@chrisdown.name> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 18, 2020 at 11:17:56AM +0100, Chris Down wrote: > I'd ask that you understand a bit more about the tradeoffs and intentions of > the patch before rushing in to declare its failure, considering it works > just fine :-) > > Clamping the maximal time allows the application to take some action to > remediate the situation, while still being slowed down significantly. 2 > seconds per allocation batch is still absolutely plenty for any use case > I've come across. If you have evidence it isn't, then present that instead > of vague notions of "wrongness". There is no feedback from the freeing rate, therefore it cannot be correct in maintaining a maximum amount of pages. 0.5 pages / sec is still non-zero, and if the free rate is 0, you'll crawl across whatever limit was set without any bounds. This is math 101. It's true that I haven't been paying attention to mm in a while, but I was one of the original authors of the I/O dirty balancing, I do think I understand how these things work.