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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 AE4B7C7618B for ; Mon, 29 Jul 2019 18:48:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8028321655 for ; Mon, 29 Jul 2019 18:48:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564426134; bh=pIMNsYM0fVCuJc3GSaOexiSH6hgAFC4uyI+oZR7lEY8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=wlCuxrBuut5/UwzoiTkLBC1AIau84aAjZqD56pZ4gt9LoUldVn2eOa1E+MAXwBv18 Rdt8E4oGXxTqaey7OTXqYgrkCgklIVLRl/P/G5mvKeNQto89Uz4qaCCiPMwbRoAPkG iT9TPTdqUh+GiR7+cvQgJ1YIY/AsqKOXm6+V8ZVo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388252AbfG2Ssx (ORCPT ); Mon, 29 Jul 2019 14:48:53 -0400 Received: from mx2.suse.de ([195.135.220.15]:54776 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725894AbfG2Ssx (ORCPT ); Mon, 29 Jul 2019 14:48:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CB20FAEFD; Mon, 29 Jul 2019 18:48:51 +0000 (UTC) Date: Mon, 29 Jul 2019 20:48:50 +0200 From: Michal Hocko To: Yang Shi Cc: Konstantin Khlebnikov , Linux MM , Linux Kernel Mailing List , cgroups@vger.kernel.org, Vladimir Davydov , Johannes Weiner Subject: Re: [PATCH RFC] mm/memcontrol: reclaim severe usage over high limit in get_user_pages loop Message-ID: <20190729184850.GH9330@dhcp22.suse.cz> References: <156431697805.3170.6377599347542228221.stgit@buzz> <20190729091738.GF9330@dhcp22.suse.cz> <3d6fc779-2081-ba4b-22cf-be701d617bb4@yandex-team.ru> <20190729103307.GG9330@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 29-07-19 10:28:43, Yang Shi wrote: [...] > I don't worry too much about scale since the scale issue is not unique > to background reclaim, direct reclaim may run into the same problem. Just to clarify. By scaling problem I mean 1:1 kswapd thread to memcg. You can have thousands of memcgs and I do not think we really do want to create one kswapd for each. Once we have a kswapd thread pool then we get into a tricky land where a determinism/fairness would be non trivial to achieve. Direct reclaim, on the other hand is bound by the workload itself. -- Michal Hocko SUSE Labs