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=-3.9 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 389AFC433E1 for ; Tue, 18 Aug 2020 14:43:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 09C2A207DA for ; Tue, 18 Aug 2020 14:43:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="f3Eeeieg"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="bo7hO/Wx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726585AbgHROnR (ORCPT ); Tue, 18 Aug 2020 10:43:17 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:59738 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726145AbgHROnR (ORCPT ); Tue, 18 Aug 2020 10:43:17 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1597761795; 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: in-reply-to:in-reply-to:references:references; bh=SppHSehsQnzHNR4Hp31ymdWpJXvQcn4y9IMbNmCLF/o=; b=f3Eeeieg1bgFpw7sMFjJEVif5jIWoAGf1dr0jSz592v2nZWW37NQgIMtsom2qNI9MJEhKT wDOmjoUZ3tisb40VPAHypTkfNpB3fIj3eTWpPm1A9oLITY/HK4BCARXTOuCPL+CNB5jrJS PA4bLz9V0qG49VACLa88yiGFl9wiCDoAnuBY9FVA2Fh2RM/zEt9dZQBKclxNtJHtH7W3Rm 9wJuyW6/DQ7rdF15DUzCzkouWEMp5MhigzDxWKLCe+dLV8TLwB5o0v0iLwFQ5bUOqKVgh3 ltPKEcEvGq/nlOUFqdwtOKoilwOGqHE5oXzKdorStaDucXXTn/9A9zMjKFMusQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1597761795; 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: in-reply-to:in-reply-to:references:references; bh=SppHSehsQnzHNR4Hp31ymdWpJXvQcn4y9IMbNmCLF/o=; b=bo7hO/Wxpq0YYb29xOt44+QJFstf3JBH+zt2rbE97glkrxXCHF2IuBhZyu+Z7Bn8On6+ki dZIIv++UHFiKo8BA== To: paulmck@kernel.org, Michal Hocko Cc: Uladzislau Rezki , Peter Zijlstra , LKML , RCU , linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Matthew Wilcox , "Theodore Y . Ts'o" , Joel Fernandes , Sebastian Andrzej Siewior , Oleksiy Avramchenko Subject: Re: [RFC-PATCH 1/2] mm: Add __GFP_NO_LOCKS flag In-Reply-To: <20200818135327.GF23602@paulmck-ThinkPad-P72> References: <20200814161106.GA13853@paulmck-ThinkPad-P72> <20200814174924.GI3982@worktop.programming.kicks-ass.net> <20200814180224.GQ4295@paulmck-ThinkPad-P72> <875z9lkoo4.fsf@nanos.tec.linutronix.de> <20200814204140.GT4295@paulmck-ThinkPad-P72> <20200814215206.GL3982@worktop.programming.kicks-ass.net> <20200816225655.GA17869@pc636> <20200817082849.GA28270@dhcp22.suse.cz> <20200817222803.GE23602@paulmck-ThinkPad-P72> <20200818074344.GL28270@dhcp22.suse.cz> <20200818135327.GF23602@paulmck-ThinkPad-P72> Date: Tue, 18 Aug 2020 16:43:14 +0200 Message-ID: <87o8n8hv5p.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Tue, Aug 18 2020 at 06:53, Paul E. McKenney wrote: > On Tue, Aug 18, 2020 at 09:43:44AM +0200, Michal Hocko wrote: >> Thomas had a good point that it doesn't really make much sense to >> optimize for flooders because that just makes them more effective. > > The point is not to make the flooders go faster, but rather for the > system to be robust in the face of flooders. Robust as in harder for > a flooder to OOM the system. > > And reducing the number of post-grace-period cache misses makes it > easier for the callback-invocation-time memory freeing to keep up with > the flooder, thus avoiding (or at least delaying) the OOM. Throttling the flooder is incresing robustness far more than reducing cache misses. Thanks, tglx