Re: [PATCH 1/4] mm: pass set_count and set_reserved to __init_single_page

[Yajun Deng]

On 2023/9/22 16:08, Mike Rapoport wrote:
> On Fri, Sep 22, 2023 at 09:48:59AM +0200, David Hildenbrand wrote:
> > On 22.09.23 09:47, Matthew Wilcox wrote:
> > > On Fri, Sep 22, 2023 at 03:09:20PM +0800, Yajun Deng wrote:
> > > > -		__init_single_page(page, pfn, zone, nid);
> > > > +		__init_single_page(page, pfn, zone, nid, true, false);
> > > So Linus has just had a big rant about not doing bool flags to
> > > functions.  And in particular _multiple_ bool flags to functions.
> > >
> > > ie this should be:
> > >
> > > #define INIT_PAGE_COUNT		(1 << 0)
> > > #define INIT_PAGE_RESERVED	(1 << 1)
> > >
> > > 		__init_single_page(page, pfn, zone, nid, INIT_PAGE_COUNT);
> > >
> > > or something similar.
> > >
> > > I have no judgement on the merits of this patch so far.  Do you have
> > > performance numbers for each of these patches?  Some of them seem quite
> > > unlikely to actually help, at least on a machine which is constrained
> > > by cacheline fetches.
> > The last patch contains
> >
> > before:
> > node 0 deferred pages initialised in 78ms
> >
> > after:
> > node 0 deferred pages initialised in 72ms
> >
> > Not earth-shattering :D Maybe with much bigger machines relevant?
> Patch 3 contains
>
> The following data was tested on an x86 machine with 190GB of RAM.
>
> before:
> free_low_memory_core_early()    342ms
>
> after:
> free_low_memory_core_early()    286ms
>
> Which is more impressive, but still I'm not convinced that it's worth the
> added complexity and potential subtle bugs.
I will send v2.  It will be simpler and safer.
> > --
> > Cheers,
> >
> > David / dhildenb