From patchwork Mon Dec 16 12:45:24 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 11294115 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 9AA8C1580 for ; Mon, 16 Dec 2019 12:46:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 749C520725 for ; Mon, 16 Dec 2019 12:46:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="Pc1iCDrx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727689AbfLPMqS (ORCPT ); Mon, 16 Dec 2019 07:46:18 -0500 Received: from smtp-fw-9102.amazon.com ([207.171.184.29]:61686 "EHLO smtp-fw-9102.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727605AbfLPMqS (ORCPT ); Mon, 16 Dec 2019 07:46:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1576500378; x=1608036378; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=6HH7PeknGCYANJeR4Z4A5j/5EdY1wACfauzPdOr50Ks=; b=Pc1iCDrxxJ5Glj6IYboPnLJbHG/I8hyMwKvTfxRlOKaeI5lV/yJ4BIxZ 8cwjfQIK5PRW1uT204Amc2Td61IGeflzZ+k0Xv32pGYev31+ipOsTWAul c2R2x5xKgfypg5dOzyuFVXh/nW3iosEZ6/oswbwjPzpPB0kOSNGU6X9Re 4=; IronPort-SDR: 5jRD8qD7U5ldv+4JIsbZMv8BTLTGVuKPdQuh8w1XC8skDaoJA0aFJxD3wynKNkrM0uceo2SXUq rqk0WmPOxp6Q== X-IronPort-AV: E=Sophos;i="5.69,321,1571702400"; d="scan'208";a="13761382" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2b-81e76b79.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 16 Dec 2019 12:46:07 +0000 Received: from EX13MTAUEA001.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2b-81e76b79.us-west-2.amazon.com (Postfix) with ESMTPS id 5D242A1F17; Mon, 16 Dec 2019 12:46:05 +0000 (UTC) Received: from EX13D31EUA001.ant.amazon.com (10.43.165.15) by EX13MTAUEA001.ant.amazon.com (10.43.61.243) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 16 Dec 2019 12:46:04 +0000 Received: from u886c93fd17d25d.ant.amazon.com (10.43.160.100) by EX13D31EUA001.ant.amazon.com (10.43.165.15) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 16 Dec 2019 12:45:59 +0000 From: SeongJae Park To: , , , CC: SeongJae Park , , , , , , Subject: [PATCH v10 1/4] xenbus/backend: Add memory pressure handler callback Date: Mon, 16 Dec 2019 13:45:24 +0100 Message-ID: <20191216124527.30306-2-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191216124527.30306-1-sjpark@amazon.com> References: <20191216124527.30306-1-sjpark@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.160.100] X-ClientProxiedBy: EX13D17UWC002.ant.amazon.com (10.43.162.61) To EX13D31EUA001.ant.amazon.com (10.43.165.15) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 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)