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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 76B48C43603 for ; Tue, 10 Dec 2019 08:17:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49F2320663 for ; Tue, 10 Dec 2019 08:17:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727067AbfLJIRl (ORCPT ); Tue, 10 Dec 2019 03:17:41 -0500 Received: from mx2.suse.de ([195.135.220.15]:38224 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727048AbfLJIRl (ORCPT ); Tue, 10 Dec 2019 03:17:41 -0500 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 9CC40B321; Tue, 10 Dec 2019 08:17:39 +0000 (UTC) Subject: Re: [PATCH v5 1/2] xenbus/backend: Add memory pressure handler callback To: SeongJae Park , sjpark@amazon.com Cc: axboe@kernel.dk, konrad.wilk@oracle.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, pdurrant@amazon.com, roger.pau@citrix.com, xen-devel@lists.xenproject.org, SeongJae Park References: <20191210080628.5264-1-sjpark@amazon.de> <20191210080628.5264-2-sjpark@amazon.de> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <7260cdce-7488-5045-0572-021a0ef191ac@suse.com> Date: Tue, 10 Dec 2019 09:17:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <20191210080628.5264-2-sjpark@amazon.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 10.12.19 09:06, SeongJae Park wrote: > Granting pages consumes backend system memory. In systems configured > with insufficient spare memory for those pages, it can cause a memory > pressure situation. However, finding the optimal amount of the spare > memory is challenging for large systems having dynamic resource > utilization patterns. Also, such a static configuration might lack a > flexibility. > > To mitigate such problems, this commit adds a memory reclaim callback to > 'xenbus_driver'. Using this facility, 'xenbus' would be able to monitor > a memory pressure and request specific devices of specific backend > drivers which causing the given pressure to voluntarily release its > memory. > > That said, this commit simply requests every callback registered driver > to release its memory for every domain, rather than issueing the > requests to the drivers and the domain in charge. Such things will be > done in a futur. Also, this commit focuses on memory only. However, it > would be ablt to be extended for general resources. > > Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross Juergen