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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 12AE7C3B1AD for ; Fri, 13 Dec 2019 20:38:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47005246D0 for ; Fri, 13 Dec 2019 20:38:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Ixr1uzWS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727988AbfLMPgH (ORCPT ); Fri, 13 Dec 2019 10:36:07 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:46112 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727831AbfLMPgH (ORCPT ); Fri, 13 Dec 2019 10:36:07 -0500 Received: by mail-pg1-f196.google.com with SMTP id z124so1730173pgb.13; Fri, 13 Dec 2019 07:36:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=pxUD+VmkH1xxeAkPK92Cf10G5edui36/X8Za7R/dfvU=; b=Ixr1uzWSZhFf+lN6eqJRIzN6Nk/Q8MV4OUDFeqLklPVBvYba8reW18kTv4gIt2ty7W YFl4vqgRekirFS4RrCr28ScdT33deONmVd7zkU6xVyc+pjs87f8I9KQSebt2RinCiIiJ IfsHoNp5B9Ph+o7K1MKkspCPMOY4lSrYC654aGCs18gfIgwl29eKV9qlUoT3BDhB9au/ creQfHb91b5xQ36j0Sl3Vr7OGSEXrM0cP+Re4OLVvxeOzKspYWT8Yso1bdSDNp2MZ7St R2iaDm9wu9Ez8nhDb4+Ailbv3qEUPdfnayJsJGNSy650S5txnbwbgw3OJG1/RK52m3K4 zZaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=pxUD+VmkH1xxeAkPK92Cf10G5edui36/X8Za7R/dfvU=; b=C+8ruMvR2TbKDlPLGXnByYm8tJsKp2x80+HO5IBsvncujsVOKyOWzz3Z3amQ2W79aG JN6z7rhM8M/DGZFYwv/jNVbCMR1vEol9oHAVCs0SfW0RSC1mX8fXtBa0ezeIclMy+IhF 5lm/THd6PB3ISINDAZ43nwnxKezJrhM+IDWZM8dR66LtgZBps/XTwmGuyB4mil5+Yiax 6r6qKcTlTRCi9rQ04iNbGPU03o6yL/NUoRFWPgdAv8yGXF5TcQdxda5l1CfyirvKHnpW cJhafRDJnVG0btb1kOeNDxuMhMudAV6aqT0dNNmd3gy5btje0Yn3R2TjDSYyR2V7t4YL p8Jg== X-Gm-Message-State: APjAAAVHWaRqw1QhnCwE1QiRdz73wNVX3YQaLhGRGxtY612nxBrDunm0 C5d7hDbSVnaa61dBZOulJRY= X-Google-Smtp-Source: APXvYqxeZnSOB6LMFmDPGKrs65/NbWggTkEtyDaKTMLASFru59pOpOU1EFfyJv/RlrSyRw6JhLA9uw== X-Received: by 2002:a65:6245:: with SMTP id q5mr17688689pgv.347.1576251366306; Fri, 13 Dec 2019 07:36:06 -0800 (PST) Received: from localhost.localdomain ([12.176.148.120]) by smtp.gmail.com with ESMTPSA id w131sm12039217pfc.16.2019.12.13.07.36.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Dec 2019 07:36:05 -0800 (PST) From: SeongJae Park X-Google-Original-From: SeongJae Park To: jgross@suse.com, axboe@kernel.dk, konrad.wilk@oracle.com, roger.pau@citrix.com Cc: SeongJae Park , pdurrant@amazon.com, sjpark@amazon.com, sj38.park@gmail.com, xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v9 1/4] xenbus/backend: Add memory pressure handler callback Date: Fri, 13 Dec 2019 15:35:43 +0000 Message-Id: <20191213153546.17425-2-sjpark@amazon.de> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191213153546.17425-1-sjpark@amazon.de> References: <20191213153546.17425-1-sjpark@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 flexibility. To mitigate such problems, this commit adds a memory reclaim callback to 'xenbus_driver'. If a memory pressure is detected, 'xenbus' requests every backend driver to volunarily release its memory. Note that it would be able to improve the callback facility for more sophisticated handlings of general pressures. For example, it would be possible to monitor the memory consumption of each device and issue the release requests to only devices which causing the pressure. Also, the callback could be extended to handle not only memory, but general resources. Nevertheless, this version of the implementation defers such sophisticated goals as a future work. Reviewed-by: Juergen Gross Reviewed-by: Roger Pau Monné Signed-off-by: SeongJae Park --- drivers/xen/xenbus/xenbus_probe_backend.c | 32 +++++++++++++++++++++++ include/xen/xenbus.h | 1 + 2 files changed, 33 insertions(+) diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c index b0bed4faf44c..7e78ebef7c54 100644 --- a/drivers/xen/xenbus/xenbus_probe_backend.c +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -248,6 +248,35 @@ static int backend_probe_and_watch(struct notifier_block *notifier, return NOTIFY_DONE; } +static int backend_reclaim_memory(struct device *dev, void *data) +{ + const struct xenbus_driver *drv; + + if (!dev->driver) + return 0; + drv = to_xenbus_driver(dev->driver); + if (drv && drv->reclaim_memory) + drv->reclaim_memory(to_xenbus_device(dev)); + return 0; +} + +/* + * Returns 0 always because we are using shrinker to only detect memory + * pressure. + */ +static unsigned long backend_shrink_memory_count(struct shrinker *shrinker, + struct shrink_control *sc) +{ + bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, + backend_reclaim_memory); + return 0; +} + +static struct shrinker backend_memory_shrinker = { + .count_objects = backend_shrink_memory_count, + .seeks = DEFAULT_SEEKS, +}; + static int __init xenbus_probe_backend_init(void) { static struct notifier_block xenstore_notifier = { @@ -264,6 +293,9 @@ static int __init xenbus_probe_backend_init(void) register_xenstore_notifier(&xenstore_notifier); + if (register_shrinker(&backend_memory_shrinker)) + pr_warn("shrinker registration failed\n"); + return 0; } subsys_initcall(xenbus_probe_backend_init); diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h index 869c816d5f8c..c861cfb6f720 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -104,6 +104,7 @@ struct xenbus_driver { struct device_driver driver; int (*read_otherend_details)(struct xenbus_device *dev); int (*is_ready)(struct xenbus_device *dev); + void (*reclaim_memory)(struct xenbus_device *dev); }; static inline struct xenbus_driver *to_xenbus_driver(struct device_driver *drv) -- 2.17.1