On Wed 05-09-18 13:18:24, Alexander Duyck wrote: > On Tue, Sep 4, 2018 at 11:24 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > On Tue 04-09-18 11:33:45, Alexander Duyck wrote: > > > From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> > > > > > > It doesn't make much sense to use the atomic SetPageReserved at init time > > > when we are using memset to clear the memory and manipulating the page > > > flags via simple "&=" and "|=" operations in __init_single_page. > > > > > > This patch adds a non-atomic version __SetPageReserved that can be used > > > during page init and shows about a 10% improvement in initialization times > > > on the systems I have available for testing. > > > > I agree with Dave about a comment is due. I am also quite surprised that > > this leads to such a large improvement. Could you be more specific about > > your test and machines you were testing on? > > So my test case has been just initializing 4 3TB blocks of persistent > memory with a few trace_printk values added to track total time in > move_pfn_range_to_zone. > > What I have been seeing is that the time needed for the call drops on > average from 35-36 seconds down to around 31-32. This information belongs to the changelog. > > > Other than that the patch makes sense to me. > > > > > Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> > > > > With the above addressed, feel free to add > > Acked-by: Michal Hocko <mhocko@xxxxxxxx> > > > > Thanks! > > As far as adding a comment are we just talking about why it is > reserved, or do we need a description of the __SetPageReserved versus > SetPageReserved. For now I was looking at adding a comment like: the later. The reason why we make it reserved should be quite clear. A comment wouldn't hurt of course and what you have is a good start. But it is usually atomic vs. non-atomic SetPage$Foo which needs some clarification. > @@ -5517,8 +5517,13 @@ void __meminit memmap_init_zone(unsigned long > size, int nid, unsigned long zone, > not_early: > page = pfn_to_page(pfn); > __init_single_page(page, pfn, zone, nid); > + > + /* > + * Mark page reserved as it will need to wait for onlining > + * phase for it to be fully associated with a zone. > + */ > if (context == MEMMAP_HOTPLUG) > - SetPageReserved(page); > + __SetPageReserved(page); > > /* > * Mark the block movable so that blocks are reserved for > > Any thoughts on this? > > Thanks. > > - Alex -- Michal Hocko SUSE Labs
