From patchwork Mon Jan 27 08:18:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 11352197 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F1A11159A for ; Mon, 27 Jan 2020 08:21:01 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CDD912168B for ; Mon, 27 Jan 2020 08:21:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="C1irDws5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDD912168B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ivzbv-0001Xk-HP; Mon, 27 Jan 2020 08:19:07 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ivzbu-0001XT-8d for xen-devel@lists.xenproject.org; Mon, 27 Jan 2020 08:19:06 +0000 X-Inumbo-ID: ae3d2bde-40dd-11ea-84ee-12813bfff9fa Received: from smtp-fw-33001.amazon.com (unknown [207.171.190.10]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id ae3d2bde-40dd-11ea-84ee-12813bfff9fa; Mon, 27 Jan 2020 08:19:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1580113145; x=1611649145; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=AlgYXHZVMr+gkDp34KurcKlh0X9TRVaRFfmS+SsrAhM=; b=C1irDws5oV09JZu3Z4+RnpzDvptNqC3q5AsPRJfnXLmfWm85gqM1OS3x p8kvT/KlSNrH4sWqJi6dZoaROGB2XLl1uxpD86SudngKcnmK4L2LuDNI7 XGGQ4LW7Lg2cDvIlocCKb/GRd/ezUe3idtJo8RmeTewzYPsm4YpECXiW+ U=; IronPort-SDR: uMkQlNiB9w5LHs1zA7FOvJdLJiQC00IV2UorSjll8vNCEJaZKnmwAqbu3FMlvy4oKtfAHCugov 90/hYLNt0awA== X-IronPort-AV: E=Sophos;i="5.70,369,1574121600"; d="scan'208";a="22599795" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2c-397e131e.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-33001.sea14.amazon.com with ESMTP; 27 Jan 2020 08:18:43 +0000 Received: from EX13MTAUEA002.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2c-397e131e.us-west-2.amazon.com (Postfix) with ESMTPS id BBF46A22CE; Mon, 27 Jan 2020 08:18:42 +0000 (UTC) Received: from EX13D31EUA001.ant.amazon.com (10.43.165.15) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1236.3; Mon, 27 Jan 2020 08:18:42 +0000 Received: from u886c93fd17d25d.ant.amazon.com (10.43.160.8) by EX13D31EUA001.ant.amazon.com (10.43.165.15) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 27 Jan 2020 08:18:37 +0000 From: To: , , Date: Mon, 27 Jan 2020 09:18:08 +0100 Message-ID: <20200127081812.21216-2-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200127081812.21216-1-sjpark@amazon.com> References: <20200127081812.21216-1-sjpark@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.160.8] X-ClientProxiedBy: EX13D11UWB004.ant.amazon.com (10.43.161.90) To EX13D31EUA001.ant.amazon.com (10.43.165.15) Precedence: Bulk Subject: [Xen-devel] [PATCH v14 1/5] xenbus/backend: Add memory pressure handler callback X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: konrad.wilk@oracle.com, pdurrant@amazon.com, SeongJae Park , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" From: SeongJae Park 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 14876faff3b0..3b5cb7a5a7e4 100644 --- a/drivers/xen/xenbus/xenbus_probe_backend.c +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -247,6 +247,35 @@ 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 = { @@ -263,6 +292,9 @@ 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 24228a102141..980952ea452b 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -105,6 +105,7 @@ 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)