From patchwork Wed Sep 23 06:18:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 11794047 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 31886112C for ; Wed, 23 Sep 2020 06:19:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 159CF21D43 for ; Wed, 23 Sep 2020 06:19:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="c5Oa9jDD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726647AbgIWGTX (ORCPT ); Wed, 23 Sep 2020 02:19:23 -0400 Received: from smtp-fw-33001.amazon.com ([207.171.190.10]:21096 "EHLO smtp-fw-33001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726643AbgIWGTW (ORCPT ); Wed, 23 Sep 2020 02:19:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1600841963; x=1632377963; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=qIdI2Ar+FjlI0h5NCqVRr5Ean1G5IGrdck+ZoSf7G0w=; b=c5Oa9jDDccuvfyfRuSH9Krksx/ZUvGQ0gBmDj5i+/RIflRz8g4nx+eSJ tNB6BALvyelgRch8RKsyFiUTg7oGHcCQDZiT9reJGpGHbgFwofaoKj/IG v3EM8/CzQQ8PnXJ4jArHlwOEt2/4fe+qyn3TSWXwf/ZwlyVhF53ZBM1rm k=; X-IronPort-AV: E=Sophos;i="5.77,293,1596499200"; d="scan'208";a="77284083" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2a-e7be2041.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-33001.sea14.amazon.com with ESMTP; 23 Sep 2020 06:19:14 +0000 Received: from EX13D31EUA004.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan2.pdx.amazon.com [10.170.41.162]) by email-inbound-relay-2a-e7be2041.us-west-2.amazon.com (Postfix) with ESMTPS id B2778A1DEE; Wed, 23 Sep 2020 06:19:12 +0000 (UTC) Received: from u3f2cd687b01c55.ant.amazon.com (10.43.162.85) by EX13D31EUA004.ant.amazon.com (10.43.165.161) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 23 Sep 2020 06:19:06 +0000 From: SeongJae Park To: , , CC: SeongJae Park , , , , , , , , Subject: [PATCH v4 1/3] xen-blkback: add a parameter for disabling of persistent grants Date: Wed, 23 Sep 2020 08:18:39 +0200 Message-ID: <20200923061841.20531-2-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923061841.20531-1-sjpark@amazon.com> References: <20200923061841.20531-1-sjpark@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.162.85] X-ClientProxiedBy: EX13D10UWB001.ant.amazon.com (10.43.161.111) To EX13D31EUA004.ant.amazon.com (10.43.165.161) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: SeongJae Park Persistent grants feature provides high scalability. On some small systems, however, it could incur data copy overheads[1] and thus it is required to be disabled. But, there is no option to disable it. For the reason, this commit adds a module parameter for disabling of the feature. [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability Signed-off-by: Anthony Liguori Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross Acked-by: Roger Pau Monné --- .../ABI/testing/sysfs-driver-xen-blkback | 9 ++++++++ drivers/block/xen-blkback/xenbus.c | 22 ++++++++++++++----- 2 files changed, 25 insertions(+), 6 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkback b/Documentation/ABI/testing/sysfs-driver-xen-blkback index ecb7942ff146..ac2947b98950 100644 --- a/Documentation/ABI/testing/sysfs-driver-xen-blkback +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkback @@ -35,3 +35,12 @@ Description: controls the duration in milliseconds that blkback will not cache any page not backed by a grant mapping. The default is 10ms. + +What: /sys/module/xen_blkback/parameters/feature_persistent +Date: September 2020 +KernelVersion: 5.10 +Contact: SeongJae Park +Description: + Whether to enable the persistent grants feature or not. Note + that this option only takes effect on newly created backends. + The default is Y (enable). diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index b9aa5d1ac10b..8fc34211dc8b 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -474,6 +474,12 @@ static void xen_vbd_free(struct xen_vbd *vbd) vbd->bdev = NULL; } +/* Enable the persistent grants feature. */ +static bool feature_persistent = true; +module_param(feature_persistent, bool, 0644); +MODULE_PARM_DESC(feature_persistent, + "Enables the persistent grants feature"); + static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, unsigned major, unsigned minor, int readonly, int cdrom) @@ -519,6 +525,8 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, if (q && blk_queue_secure_erase(q)) vbd->discard_secure = true; + vbd->feature_gnt_persistent = feature_persistent; + pr_debug("Successful creation of handle=%04x (dom=%u)\n", handle, blkif->domid); return 0; @@ -906,7 +914,8 @@ static void connect(struct backend_info *be) xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); - err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); + err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", + be->blkif->vbd.feature_gnt_persistent); if (err) { xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", dev->nodename); @@ -1067,7 +1076,6 @@ static int connect_ring(struct backend_info *be) { struct xenbus_device *dev = be->dev; struct xen_blkif *blkif = be->blkif; - unsigned int pers_grants; char protocol[64] = ""; int err, i; char *xspath; @@ -1093,9 +1101,11 @@ static int connect_ring(struct backend_info *be) xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); return -ENOSYS; } - pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent", - 0); - blkif->vbd.feature_gnt_persistent = pers_grants; + if (blkif->vbd.feature_gnt_persistent) + blkif->vbd.feature_gnt_persistent = + xenbus_read_unsigned(dev->otherend, + "feature-persistent", 0); + blkif->vbd.overflow_max_grants = 0; /* @@ -1118,7 +1128,7 @@ static int connect_ring(struct backend_info *be) pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename, blkif->nr_rings, blkif->blk_protocol, protocol, - pers_grants ? "persistent grants" : ""); + blkif->vbd.feature_gnt_persistent ? "persistent grants" : ""); ring_page_order = xenbus_read_unsigned(dev->otherend, "ring-page-order", 0); From patchwork Wed Sep 23 06:18:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 11794049 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 5EDD992C for ; Wed, 23 Sep 2020 06:19:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B201238E5 for ; Wed, 23 Sep 2020 06:19:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="e7xQHRzb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726667AbgIWGTX (ORCPT ); Wed, 23 Sep 2020 02:19:23 -0400 Received: from smtp-fw-6001.amazon.com ([52.95.48.154]:29627 "EHLO smtp-fw-6001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726550AbgIWGTW (ORCPT ); Wed, 23 Sep 2020 02:19:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1600841961; x=1632377961; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Ugucz/rQejY9CCWX5M6IeRpnuv55lkqiEc2mhoGSlgc=; b=e7xQHRzb8qeoEGRvnMLAKTYbiMFcOUP0MTO7G7AiroG3FwvjUztWEgc7 OStvZKCM5Yq01rXS38UeOdimeG08+GLyj+70H1stzZisqEsTPCiCqPa+0 qRKppJCpkfHiHd1RtkrBQ2P8VfnPqIgEMj8VeSO9Mh2gsdmJlgrDuVc/O Y=; X-IronPort-AV: E=Sophos;i="5.77,293,1596499200"; d="scan'208";a="57152357" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2c-6f38efd9.us-west-2.amazon.com) ([10.43.8.6]) by smtp-border-fw-out-6001.iad6.amazon.com with ESMTP; 23 Sep 2020 06:19:20 +0000 Received: from EX13D31EUA004.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2c-6f38efd9.us-west-2.amazon.com (Postfix) with ESMTPS id 4117DA062F; Wed, 23 Sep 2020 06:19:19 +0000 (UTC) Received: from u3f2cd687b01c55.ant.amazon.com (10.43.162.85) by EX13D31EUA004.ant.amazon.com (10.43.165.161) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 23 Sep 2020 06:19:12 +0000 From: SeongJae Park To: , , CC: SeongJae Park , , , , , , , , Subject: [PATCH v4 2/3] xen-blkfront: add a parameter for disabling of persistent grants Date: Wed, 23 Sep 2020 08:18:40 +0200 Message-ID: <20200923061841.20531-3-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923061841.20531-1-sjpark@amazon.com> References: <20200923061841.20531-1-sjpark@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.162.85] X-ClientProxiedBy: EX13D10UWB001.ant.amazon.com (10.43.161.111) To EX13D31EUA004.ant.amazon.com (10.43.165.161) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: SeongJae Park Persistent grants feature provides high scalability. On some small systems, however, it could incur data copy overheads[1] and thus it is required to be disabled. It can be disabled from blkback side using a module parameter, 'feature_persistent'. But, it is impossible from blkfront side. For the reason, this commit adds a blkfront module parameter for disabling of the feature. [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross Acked-by: Roger Pau Monné --- .../ABI/testing/sysfs-driver-xen-blkfront | 9 +++++++++ drivers/block/xen-blkfront.c | 20 ++++++++++++++----- 2 files changed, 24 insertions(+), 5 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkfront b/Documentation/ABI/testing/sysfs-driver-xen-blkfront index c0a6cb7eb314..9c31334cb2e6 100644 --- a/Documentation/ABI/testing/sysfs-driver-xen-blkfront +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkfront @@ -8,3 +8,12 @@ Description: is 32 - higher value means more potential throughput but more memory usage. The backend picks the minimum of the frontend and its default backend value. + +What: /sys/module/xen_blkfront/parameters/feature_persistent +Date: September 2020 +KernelVersion: 5.10 +Contact: SeongJae Park +Description: + Whether to enable the persistent grants feature or not. Note + that this option only takes effect on newly created frontends. + The default is Y (enable). diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 91de2e0755ae..48629d3433b4 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1866,8 +1866,8 @@ static int talk_to_blkback(struct xenbus_device *dev, message = "writing protocol"; goto abort_transaction; } - err = xenbus_printf(xbt, dev->nodename, - "feature-persistent", "%u", 1); + err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", + info->feature_persistent); if (err) dev_warn(&dev->dev, "writing persistent grants feature to xenbus"); @@ -1941,6 +1941,13 @@ static int negotiate_mq(struct blkfront_info *info) } return 0; } + +/* Enable the persistent grants feature. */ +static bool feature_persistent = true; +module_param(feature_persistent, bool, 0644); +MODULE_PARM_DESC(feature_persistent, + "Enables the persistent grants feature"); + /** * Entry point to this code when a new device is created. Allocate the basic * structures and the ring buffer for communication with the backend, and @@ -2007,6 +2014,8 @@ static int blkfront_probe(struct xenbus_device *dev, info->vdevice = vdevice; info->connected = BLKIF_STATE_DISCONNECTED; + info->feature_persistent = feature_persistent; + /* Front end dir is a number, which is used as the id. */ info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); dev_set_drvdata(&dev->dev, info); @@ -2316,9 +2325,10 @@ static void blkfront_gather_backend_features(struct blkfront_info *info) if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) blkfront_setup_discard(info); - info->feature_persistent = - !!xenbus_read_unsigned(info->xbdev->otherend, - "feature-persistent", 0); + if (info->feature_persistent) + info->feature_persistent = + !!xenbus_read_unsigned(info->xbdev->otherend, + "feature-persistent", 0); indirect_segments = xenbus_read_unsigned(info->xbdev->otherend, "feature-max-indirect-segments", 0); From patchwork Wed Sep 23 06:18:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 11794051 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 8DAF61731 for ; Wed, 23 Sep 2020 06:19:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61E32221E8 for ; Wed, 23 Sep 2020 06:19:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="tr5KiZOD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726716AbgIWGT3 (ORCPT ); Wed, 23 Sep 2020 02:19:29 -0400 Received: from smtp-fw-9101.amazon.com ([207.171.184.25]:4753 "EHLO smtp-fw-9101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726550AbgIWGT3 (ORCPT ); Wed, 23 Sep 2020 02:19:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1600841969; x=1632377969; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=wiT0fswhZm9GV0VSgNnM0/vVGnP9KcQWX4yyYuqlSeo=; b=tr5KiZOD5XENGMLLi+NrI0H1+zPQgbTXAfVbrn4BCfx6oD6vvQwi98RK yGYZLROGqLyPOj/oo72qPfsHuBrn1BdvRGT7GACX9x54q73MEbrnteXCC Y3tBcUvHnQ3HFMDd3qGb5oCOzi9N7jTOSAXRqoFR0CY4C4nTfWXxymb2k I=; X-IronPort-AV: E=Sophos;i="5.77,293,1596499200"; d="scan'208";a="70362466" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-2b-4e24fd92.us-west-2.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9101.sea19.amazon.com with ESMTP; 23 Sep 2020 06:19:26 +0000 Received: from EX13D31EUA004.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan2.pdx.amazon.com [10.170.41.162]) by email-inbound-relay-2b-4e24fd92.us-west-2.amazon.com (Postfix) with ESMTPS id CC5CBA1CE7; Wed, 23 Sep 2020 06:19:25 +0000 (UTC) Received: from u3f2cd687b01c55.ant.amazon.com (10.43.162.85) by EX13D31EUA004.ant.amazon.com (10.43.165.161) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 23 Sep 2020 06:19:19 +0000 From: SeongJae Park To: , , CC: SeongJae Park , , , , , , , , Subject: [PATCH v4 3/3] xen-blkfront: Apply changed parameter name to the document Date: Wed, 23 Sep 2020 08:18:41 +0200 Message-ID: <20200923061841.20531-4-sjpark@amazon.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200923061841.20531-1-sjpark@amazon.com> References: <20200923061841.20531-1-sjpark@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.43.162.85] X-ClientProxiedBy: EX13D10UWB001.ant.amazon.com (10.43.161.111) To EX13D31EUA004.ant.amazon.com (10.43.165.161) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: SeongJae Park Commit 14e710fe7897 ("xen-blkfront: rename indirect descriptor parameter") changed the name of the module parameter for the maximum amount of segments in indirect requests but missed updating the document. This commit updates the document. Signed-off-by: SeongJae Park Reviewed-by: Juergen Gross Acked-by: Roger Pau Monné --- Documentation/ABI/testing/sysfs-driver-xen-blkfront | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkfront b/Documentation/ABI/testing/sysfs-driver-xen-blkfront index 9c31334cb2e6..28008905615f 100644 --- a/Documentation/ABI/testing/sysfs-driver-xen-blkfront +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkfront @@ -1,4 +1,4 @@ -What: /sys/module/xen_blkfront/parameters/max +What: /sys/module/xen_blkfront/parameters/max_indirect_segments Date: June 2013 KernelVersion: 3.11 Contact: Konrad Rzeszutek Wilk