linux-kernel - Re: [PATCH V4] NUMA:Improve the efficiency of calculating pages loss

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Message-ID: <CACZJ9cXvpw0T_0n5uzucTxK19r05-yV=irJ8OvXkZz6bLW8qBw@mail.gmail.com>
Date:   Sat, 7 Oct 2023 20:04:45 +0800
From:   Liam Ni <zhiguangni01@...il.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org, rppt@...nel.org
Cc:     dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, akpm@...ux-foundation.org
Subject: Re: [PATCH V4] NUMA:Improve the efficiency of calculating pages loss

Friendly Ping

On Mon, 11 Sept 2023 at 21:39, Liam Ni <zhiguangni01@...il.com> wrote:
>
> Optimize the way of calculating missing pages.
>
> In the previous implementation, We calculate missing pages as follows:
> 1. calculate numaram by traverse all the numa_meminfo's and for each of
> them traverse all the regions in memblock.memory to prepare for
> counting missing pages.
>
> 2. Traverse all the regions in memblock.memory again to get e820ram.
>
> 3. the missing page is (e820ram - numaram )
>
> But,it's enough to count memory in ‘memblock.memory’ that doesn't have
> the node assigned.
>
> V3:https://lore.kernel.org/all/CACZJ9cUXiWxDb6hF4JFhWe7Np82k6LopVQ+_AoGFOccN4kjJqA@mail.gmail.com/#r
> V2:https://lore.kernel.org/all/20230619075315.49114-1-zhiguangni01@gmail.com/
> V1:https://lore.kernel.org/all/20230615142016.419570-1-zhiguangni01@gmail.com/
>
> Signed-off-by: Liam Ni <zhiguangni01@...il.com>
> ---
>  arch/x86/mm/numa.c       | 33 +--------------------------------
>  include/linux/memblock.h |  1 +
>  mm/memblock.c            | 21 +++++++++++++++++++++
>  3 files changed, 23 insertions(+), 32 deletions(-)
>
> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index 2aadb2019b4f..ee5f08adfaf6 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -447,37 +447,6 @@ int __node_distance(int from, int to)
>  }
>  EXPORT_SYMBOL(__node_distance);
>
> -/*
> - * Sanity check to catch more bad NUMA configurations (they are amazingly
> - * common).  Make sure the nodes cover all memory.
> - */
> -static bool __init numa_meminfo_cover_memory(const struct numa_meminfo *mi)
> -{
> -       u64 numaram, e820ram;
> -       int i;
> -
> -       numaram = 0;
> -       for (i = 0; i < mi->nr_blks; i++) {
> -               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);
> -               if ((s64)numaram < 0)
> -                       numaram = 0;
> -       }
> -
> -       e820ram = max_pfn - absent_pages_in_range(0, max_pfn);
> -
> -       /* We seem to lose 3 pages somewhere. Allow 1M of slack. */
> -       if ((s64)(e820ram - numaram) >= (1 << (20 - PAGE_SHIFT))) {
> -               printk(KERN_ERR "NUMA: nodes only cover %LuMB of your %LuMB e820 RAM. Not used.\n",
> -                      (numaram << PAGE_SHIFT) >> 20,
> -                      (e820ram << PAGE_SHIFT) >> 20);
> -               return false;
> -       }
> -       return true;
> -}
> -
>  /*
>   * Mark all currently memblock-reserved physical memory (which covers the
>   * kernel's own memory ranges) as hot-unswappable.
> @@ -583,7 +552,7 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
>                         return -EINVAL;
>                 }
>         }
> -       if (!numa_meminfo_cover_memory(mi))
> +       if (!memblock_validate_numa_coverage(SZ_1M))
>                 return -EINVAL;
>
>         /* Finally register nodes. */
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 1c1072e3ca06..0c3a193ebc58 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -120,6 +120,7 @@ int memblock_physmem_add(phys_addr_t base, phys_addr_t size);
>  void memblock_trim_memory(phys_addr_t align);
>  bool memblock_overlaps_region(struct memblock_type *type,
>                               phys_addr_t base, phys_addr_t size);
> +bool memblock_validate_numa_coverage(const u64 limit);
>  int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size);
>  int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
>  int memblock_mark_mirror(phys_addr_t base, phys_addr_t size);
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 0863222af4a4..8f61f868bec1 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -734,6 +734,27 @@ int __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)
>         return memblock_add_range(&memblock.memory, base, size, MAX_NUMNODES, 0);
>  }
>
> +bool __init_memblock memblock_validate_numa_coverage(const u64 limit)
> +{
> +       unsigned long lose_pg = 0;
> +       unsigned long start_pfn, end_pfn;
> +       int nid, i;
> +
> +       /* calculate lose page */
> +       for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
> +               if (nid == NUMA_NO_NODE)
> +                       lose_pg += end_pfn - start_pfn;
> +       }
> +
> +       if (lose_pg >= limit) {
> +               pr_err("NUMA: We lost %ld pages.\n", lose_pg);
> +               return false;
> +       }
> +
> +       return true;
> +}
> +
> +
>  /**
>   * memblock_isolate_range - isolate given range into disjoint memblocks
>   * @type: memblock type to isolate range for
> --
> 2.25.1
>