From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f197.google.com (mail-pf1-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id 48AA88E0001 for ; Thu, 20 Sep 2018 20:16:25 -0400 (EDT) Received: by mail-pf1-f197.google.com with SMTP id b29-v6so5639289pfm.1 for ; Thu, 20 Sep 2018 17:16:25 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id i16-v6si24820386pgi.660.2018.09.20.17.16.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Sep 2018 17:16:24 -0700 (PDT) Subject: Re: [PATCH v4 5/5] nvdimm: Schedule device registration on node local to the device References: <20180920215824.19464.8884.stgit@localhost.localdomain> <20180920222951.19464.39241.stgit@localhost.localdomain> From: Alexander Duyck Message-ID: Date: Thu, 20 Sep 2018 17:16:22 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: Linux MM , Linux Kernel Mailing List , linux-nvdimm , Pasha Tatashin , Michal Hocko , Dave Jiang , Ingo Molnar , Dave Hansen , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Andrew Morton , Logan Gunthorpe , "Kirill A. Shutemov" On 9/20/2018 3:59 PM, Dan Williams wrote: > On Thu, Sep 20, 2018 at 3:31 PM Alexander Duyck > wrote: >> >> This patch is meant to force the device registration for nvdimm devices to >> be closer to the actual device. This is achieved by using either the NUMA >> node ID of the region, or of the parent. By doing this we can have >> everything above the region based on the region, and everything below the >> region based on the nvdimm bus. >> >> One additional change I made is that we hold onto a reference to the parent >> while we are going through registration. By doing this we can guarantee we >> can complete the registration before we have the parent device removed. >> >> By guaranteeing NUMA locality I see an improvement of as high as 25% for >> per-node init of a system with 12TB of persistent memory. >> >> Signed-off-by: Alexander Duyck >> --- >> drivers/nvdimm/bus.c | 19 +++++++++++++++++-- >> 1 file changed, 17 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c >> index 8aae6dcc839f..ca935296d55e 100644 >> --- a/drivers/nvdimm/bus.c >> +++ b/drivers/nvdimm/bus.c >> @@ -487,7 +487,9 @@ static void nd_async_device_register(void *d, async_cookie_t cookie) >> dev_err(dev, "%s: failed\n", __func__); >> put_device(dev); >> } >> + >> put_device(dev); >> + put_device(dev->parent); > > Good catch. The child does not pin the parent until registration, but > we need to make sure the parent isn't gone while were waiting for the > registration work to run. > > Let's break this reference count fix out into its own separate patch, > because this looks to be covering a gap that may need to be > recommended for -stable. Okay, I guess I can do that. > >> >> static void nd_async_device_unregister(void *d, async_cookie_t cookie) >> @@ -504,12 +506,25 @@ static void nd_async_device_unregister(void *d, async_cookie_t cookie) >> >> void __nd_device_register(struct device *dev) >> { >> + int node; >> + >> if (!dev) >> return; >> + >> dev->bus = &nvdimm_bus_type; >> + get_device(dev->parent); >> get_device(dev); >> - async_schedule_domain(nd_async_device_register, dev, >> - &nd_async_domain); >> + >> + /* >> + * For a region we can break away from the parent node, >> + * otherwise for all other devices we just inherit the node from >> + * the parent. >> + */ >> + node = is_nd_region(dev) ? to_nd_region(dev)->numa_node : >> + dev_to_node(dev->parent); > > Devices already automatically inherit the node of their parent, so I'm > not understanding why this is needed? That doesn't happen until you call device_add, which you don't call until nd_async_device_register. All that has been called on the device up to now is device_initialize which leaves the node at NUMA_NO_NODE.