From patchwork Fri Dec 13 15:35:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 11291121 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 81F6D6C1 for ; Fri, 13 Dec 2019 21:00:06 +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 513BC2465E for ; Fri, 13 Dec 2019 21:00:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Ixr1uzWS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 513BC2465E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.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 1ifmzC-00030l-7F; Fri, 13 Dec 2019 15:36:10 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ifmzB-00030X-4s for xen-devel@lists.xenproject.org; Fri, 13 Dec 2019 15:36:09 +0000 X-Inumbo-ID: 4775d780-1dbe-11ea-b6f1-bc764e2007e4 Received: from mail-pf1-x441.google.com (unknown [2607:f8b0:4864:20::441]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 4775d780-1dbe-11ea-b6f1-bc764e2007e4; Fri, 13 Dec 2019 15:36:07 +0000 (UTC) Received: by mail-pf1-x441.google.com with SMTP id y206so1671737pfb.0 for ; Fri, 13 Dec 2019 07:36:07 -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=D4lX5Rs3VFWqCZc5QTqGVluG/O4lkCaBa761IgohxJ9AC+b6jRhBPaP8zh76RUdh9p RDmZKBh90Y1j/b7LLiLaCF3pATfiFsmCh+uRYump3zinW4c++J/0KOaHjmVupaUzc6KY lnsDUf/4/34Q9S7hI8ILcY/HPdMbme2MqXRj4/GwcLt/qW76p9UVR2EeqQMqUx7cVhf/ Qmc3IZaVUADqBIv1UNy96335n1gIJQzxL6H28MRbVKtK0QHyxfIrtBPDqp5fWVdojlwq izOyxQcxlKvTh1lF7AtFBv2Mtc9gt2zo6j/XBe0dOupJr9xUwa8FopflJ8KS64VqnqYo 6CiQ== X-Gm-Message-State: APjAAAWypmI8HIYPiPEy80xRD+xslN6GSEx0H8WPLnrAHl2Y0P54vQdU 1rPnVpT70oIVw1qN/fidr/4= 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 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 Subject: [Xen-devel] [PATCH v9 1/4] xenbus/backend: Add memory pressure handler callback X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: linux-block@vger.kernel.org, sjpark@amazon.com, pdurrant@amazon.com, SeongJae Park , linux-kernel@vger.kernel.org, sj38.park@gmail.com, xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" 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)