From patchwork Wed Dec 18 18:37:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 11301619 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 31DD3109A for ; Wed, 18 Dec 2019 18:37:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00A232176D for ; Wed, 18 Dec 2019 18:37:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="I/0aU+mO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726998AbfLRShs (ORCPT ); Wed, 18 Dec 2019 13:37:48 -0500 Received: from smtp-fw-4101.amazon.com ([72.21.198.25]:20524 "EHLO smtp-fw-4101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726698AbfLRShs (ORCPT ); Wed, 18 Dec 2019 13:37:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1576694268; x=1608230268; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=6aYnzds9BF7bd/ktBuL6CxJjY5pmEpuzxZF1/5BjyeM=; b=I/0aU+mO4Da1I0R6mjsb2MN3Cwa+gTRva7OAA37nIjS4wpqC9TE95KdT nb9c0x9MdgDOPdoYHRYJ+XH/zJoYAC25Nd7SS4FE7lS3TFEH/jhpa1z6x HMwU+AltiFQOG/hjdN7oqN2hvfrkyN5whNeXblPpp2m3XWdROVhe6mEm1 I=; IronPort-SDR: XQPrqb/oNc03XfSNsIFpBqjAx3UW2KfrL9lLsvXIYbxL8I597b9H8rXHCUirM9tac4Kf/l+32z Dl7AwWb7xp9A== X-IronPort-AV: E=Sophos;i="5.69,330,1571702400"; d="scan'208";a="9082721" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2b-55156cd4.us-west-2.amazon.com) ([10.43.8.6]) by smtp-border-fw-out-4101.iad4.amazon.com with ESMTP; 18 Dec 2019 18:37:46 +0000 Received: from EX13MTAUEA001.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan2.pdx.amazon.com [10.170.41.162]) by email-inbound-relay-2b-55156cd4.us-west-2.amazon.com (Postfix) with ESMTPS id 35CF9A2511; Wed, 18 Dec 2019 18:37:44 +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; Wed, 18 Dec 2019 18:37:43 +0000 Received: from u886c93fd17d25d.ant.amazon.com (10.43.160.109) by EX13D31EUA001.ant.amazon.com (10.43.165.15) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Wed, 18 Dec 2019 18:37:38 +0000 From: SeongJae Park To: , , , CC: SeongJae Park , , , , , Subject: [PATCH v13 0/5] xenbus/backend: Add memory pressure handler callback Date: Wed, 18 Dec 2019 19:37:13 +0100 Message-ID: <20191218183718.31719-1-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.43.160.109] X-ClientProxiedBy: EX13D10UWB003.ant.amazon.com (10.43.161.106) 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 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 patchset adds a memory reclaim callback to 'xenbus_driver' (patch 1) and then introduce a lock for race condition avoidance (patch 2). After that, patch 3 applies the callback mechanism to mitigate the problem in 'xen-blkback'. The fourth and fifth patches are trivial cleanups; those fix nits we found during the development of this patchset. Note that patches 1, 4, and 5 are not changed since v9. Base Version ------------ This patch is based on v5.4. A complete tree is also available at my public git repo: https://github.com/sjp38/linux/tree/patches/blkback/buffer_squeeze/v13 Patch History ------------- Changes from v12 (https://lore.kernel.org/xen-devel/20191218104232.9606-1-sjpark@amazon.com/) - Do not unnecessarily disable interrupts (suggested by Juergen) - Hold lock from xenbus side (suggested by Juergen) Changes from v11 (https://lore.kernel.org/xen-devel/20191217160748.693-2-sjpark@amazon.com/) - Fix wrong trylock use (reported by Juergen) - Merge patch 3 and 4 (suggested by Juergen) - Update test result Changes from v10 (https://lore.kernel.org/xen-devel/20191216124527.30306-1-sjpark@amazon.com/) - Fix race condition (reported by SeongJae, suggested by Juergen) Changes from v9 (https://lore.kernel.org/xen-devel/20191213153546.17425-1-sjpark@amazon.de/) - Add 'Reviewed-by' and 'Acked-by' from Roger Pau Monné - Update the commit message for overhead test of the 2nd path Changes from v8 (https://lore.kernel.org/xen-devel/20191213130211.24011-1-sjpark@amazon.de/) - Drop 'Reviewed-by: Juergen' from the second patch (suggested by Roger Pau Monné) - Update contact of the new module param to SeongJae Park (suggested by Roger Pau Monné) - Wordsmith the description of the parameter (suggested by Roger Pau Monné) - Fix dumb bugs (suggested by Roger Pau Monné) - Move module param definition to xenbus.c and reduce the number of lines for this change (suggested by Roger Pau Monné) - Add a comment for the new callback, reclaim_memory, as other callbacks also have - Add another trivial cleanup of xenbus.c file (4th patch) Changes from v7 (https://lore.kernel.org/xen-devel/20191211181016.14366-1-sjpark@amazon.de/) - Update sysfs-driver-xen-blkback for new parameter (suggested by Roger Pau Monné) - Use per-xen_blkif buffer_squeeze_end instead of global variable (suggested by Roger Pau Monné) Changes from v6 (https://lore.kernel.org/linux-block/20191211042428.5961-1-sjpark@amazon.de/) - Remove more unnecessary prefixes (suggested by Roger Pau Monné) - Constify a variable (suggested by Roger Pau Monné) - Rename 'reclaim' into 'reclaim_memory' (suggested by Roger Pau Monné) - More wordsmith of the commit message (suggested by Roger Pau Monné) Changes from v5 (https://lore.kernel.org/linux-block/20191210080628.5264-1-sjpark@amazon.de/) - Wordsmith the commit messages (suggested by Roger Pau Monné) - Change the reclaim callback return type (suggested by Roger Pau Monné) - Change the type of the blkback squeeze duration variable (suggested by Roger Pau Monné) - Add a patch for removal of unnecessary static variable name prefixes (suggested by Roger Pau Monné) - Fix checkpatch.pl warnings Changes from v4 (https://lore.kernel.org/xen-devel/20191209194305.20828-1-sjpark@amazon.com/) - Remove domain id parameter from the callback (suggested by Juergen Gross) - Rename xen-blkback module parameter (suggested by Stefan Nuernburger) Changes from v3 (https://lore.kernel.org/xen-devel/20191209085839.21215-1-sjpark@amazon.com/) - Add general callback in xen_driver and use it (suggested by Juergen Gross) Changes from v2 (https://lore.kernel.org/linux-block/af195033-23d5-38ed-b73b-f6e2e3b34541@amazon.com) - Rename the module parameter and variables for brevity (aggressive shrinking -> squeezing) Changes from v1 (https://lore.kernel.org/xen-devel/20191204113419.2298-1-sjpark@amazon.com/) - Adjust the description to not use the term, `arbitrarily` (suggested by Paul Durrant) - Specify time unit of the duration in the parameter description, (suggested by Maximilian Heyne) - Change default aggressive shrinking duration from 1ms to 10ms - Merge two patches into one single patch SeongJae Park (5): xenbus/backend: Add memory pressure handler callback xenbus/backend: Protect xenbus callback with lock xen/blkback: Squeeze page pools if a memory pressure is detected xen/blkback: Remove unnecessary static variable name prefixes xen/blkback: Consistently insert one empty line between functions .../ABI/testing/sysfs-driver-xen-blkback | 10 +++++ drivers/block/xen-blkback/blkback.c | 42 +++++++++---------- drivers/block/xen-blkback/common.h | 1 + drivers/block/xen-blkback/xenbus.c | 28 ++++++++++--- drivers/xen/xenbus/xenbus_probe.c | 8 +++- drivers/xen/xenbus/xenbus_probe_backend.c | 38 +++++++++++++++++ include/xen/xenbus.h | 3 ++ 7 files changed, 103 insertions(+), 27 deletions(-)