Re: [PATCH] x86,NUMA:Get the number of ram pages directly in numa_meminfo_cover_memory()

From: Mike Rapoport
Date: Sun Jun 18 2023 - 03:09:41 EST


On Sat, Jun 17, 2023 at 06:47:11PM +0800, Liam Ni wrote:
> On Fri, 16 Jun 2023 at 01:00, Mike Rapoport <rppt@xxxxxxxxxx> wrote:
> >
> > On Fri, Jun 16, 2023 at 12:20:16AM +1000, Liam Ni wrote:
> > > In a previous implementation,The ram page is calculated
> > > by counting the number of holes,
> > > however,the number of ram pages is calculated during hole calculation.
> > > Therefore,we can directly calculate the amount of ram pages.
> > >
> > > Signed-off-by: Liam Ni <zhiguangni01@xxxxxxxxx>
> > > ---
> > > arch/x86/mm/numa.c | 4 ++--
> > > include/linux/mm.h | 4 ++++
> > > mm/mm_init.c | 33 +++++++++++++++++++++++++++++++++
> > > 3 files changed, 39 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> > > index 2aadb2019b4f..8ea0e956e3d7 100644
> > > --- a/arch/x86/mm/numa.c
> > > +++ b/arch/x86/mm/numa.c
> > > @@ -461,12 +461,12 @@ static bool __init numa_meminfo_cover_memory(const struct numa_meminfo *mi)
> > > u64 s = mi->blk[i].start >> PAGE_SHIFT;
> > > u64 e = mi->blk[i].end >> PAGE_SHIFT;
> > > numaram += e - s;
> > > - numaram -= __absent_pages_in_range(mi->blk[i].nid, s, e);
> > > + numaram += __available_pages_in_range(mi->blk[i].nid, s, e);
> >
> > This is wrong. You add number of pages in range core MM sees to the number
> > of pages covered by the numa_meminfo.
> >
> > More generally, rather than traverse all the numa_meminfo's and for each of
> > them traverse all the regions in memblock.memory it's enough to count
> > memory in memblock that doesn't have the node assigned and compare it to
> > memblock_phys_mem_size().
>
> Logic like below?
> static bool __init numa_meminfo_cover_memory(const struct numa_meminfo *mi)
> {
> u64 error_value;
> error_value = pages_without_nid_in_range(0,max_pfn);
> if ((error_value ) >= (1 << (20 - PAGE_SHIFT))) {
> //print error information
> return false;
> }
> return true;
> }
>
> I can't figure out why compare it with memblock_phys_mem_size().
> The number of pages in memblock that doesn't have the node
> assigned,which also means that these pages are not in numa_info.
> So these pages can represent the number of lose pages.

Yes, there is no need to compare with memblock_phys_mem_size() if you count
pages that don't have nid set in memblock.

> Thanks
> Liam Ni

--
Sincerely yours,
Mike.