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 <richard.weiyang@xxxxxxxxx> >> --- >> 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
