On 9/5/18 4:18 PM, 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. Just curious why is there variance? During boot time is usually pretty consistent, as there is only one thread and system is in pretty much the same state. A dmesg output in the commit log would be helpful. Thank you, Pavel > >> 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: > @@ -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 >
