From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 033FD6B7396 for ; Wed, 5 Dec 2018 04:23:22 -0500 (EST) Received: by mail-ed1-f72.google.com with SMTP id b3so9586091edi.0 for ; Wed, 05 Dec 2018 01:23:21 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id m13sor10936286edm.0.2018.12.05.01.23.20 for (Google Transport Security); Wed, 05 Dec 2018 01:23:20 -0800 (PST) Date: Wed, 5 Dec 2018 09:23:19 +0000 From: Wei Yang Subject: Re: [PATCH 2/2] core-api/memory-hotplug.rst: divide Locking Internal section by different locks Message-ID: <20181205092319.nl772drzhpezcgt2@master> Reply-To: Wei Yang References: <20181205023426.24029-1-richard.weiyang@gmail.com> <20181205023426.24029-2-richard.weiyang@gmail.com> <570e4080-8c35-3de4-9ee6-8a508a2a4649@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <570e4080-8c35-3de4-9ee6-8a508a2a4649@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: David Hildenbrand Cc: Wei Yang , mhocko@suse.com, osalvador@suse.de, akpm@linux-foundation.org, linux-doc@vger.kernel.org, linux-mm@kvack.org On Wed, Dec 05, 2018 at 09:08:47AM +0100, David Hildenbrand wrote: >On 05.12.18 03:34, Wei Yang wrote: >> Currently locking for memory hotplug is a little complicated. >> >> Generally speaking, we leverage the two global lock: >> >> * device_hotplug_lock >> * mem_hotplug_lock >> >> to serialise the process. >> >> While for the long term, we are willing to have more fine-grained lock >> to provide higher scalability. >> >> This patch divides Locking Internal section based on these two global >> locks to help readers to understand it. Also it adds some new finding to >> enrich it. >> >> [David: words arrangement] >> >> Signed-off-by: Wei Yang >> --- >> Documentation/core-api/memory-hotplug.rst | 27 ++++++++++++++++++++++++--- >> 1 file changed, 24 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/core-api/memory-hotplug.rst b/Documentation/core-api/memory-hotplug.rst >> index de7467e48067..95662b283328 100644 >> --- a/Documentation/core-api/memory-hotplug.rst >> +++ b/Documentation/core-api/memory-hotplug.rst >> @@ -89,6 +89,20 @@ NOTIFY_STOP stops further processing of the notification queue. >> Locking Internals >> ================= >> >> +There are three locks involved in memory-hotplug, two global lock and one local >> +lock: >> + >> +- device_hotplug_lock >> +- mem_hotplug_lock >> +- device_lock >> + > >Do we really only ever use these three and not anything else when >adding/removing/onlining/offlining memory? > >(I am thinking e.g. about pgdat_resize_lock) Yes there are more than those three, pgdat_resize_lock is one of them. > >If so, you should phrase that maybe more generally Or add more details :) Yep, while I don't get a whole picture about the pgdat_resize_lock. The usage of this lock scatter in many places. > >"In addition to fine grained locks like pgdat_resize_lock, there are >three locks involved ..." > Sounds better :-) -- Wei Yang Help you, Help me