Re: [RFC PATCH] mm: introduce gen information in /proc/xxx/smaps

[Zhaoyang Huang]

loop yu.zhao

On Wed, Jun 26, 2024 at 4:46 PM zhaoyang.huang
<zhaoyang.huang@xxxxxxxxxx> wrote:
>
> From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
>
> Madvise_cold_and_pageout could break the LRU's balance by
> colding or moving the folio without taking activity information into
> consideration. This commit would like to introduce the folios' gen
> information based on VMA block via which the userspace could query
> the VA's activity before madvise.
>
> eg. The VMA(56c00000-56e14000) which has big Rss/Gen value suggest that
> it possesses larger proportion active folios than VMA(70dd7000-71090000)
> does and is not good candidate for madvise.
>
> 56c00000-56e14000 rw-p 00000000 00:00 0                                  [anon:dalvik-/system/framework/oat/arm64/services.art]
> Size:               2128 kB
> KernelPageSize:        4 kB
> MMUPageSize:           4 kB
> Rss:                2128 kB
> Pss:                2128 kB
> Pss_Dirty:          2128 kB
> Shared_Clean:          0 kB
> Shared_Dirty:          0 kB
> Private_Clean:         0 kB
> Private_Dirty:      2128 kB
> Referenced:         2128 kB
> Anonymous:          2128 kB
> KSM:                   0 kB
> LazyFree:              0 kB
> AnonHugePages:         0 kB
> ShmemPmdMapped:        0 kB
> FilePmdMapped:         0 kB
> Shared_Hugetlb:        0 kB
> Private_Hugetlb:       0 kB
> Swap:                  0 kB
> SwapPss:               0 kB
> Locked:                0 kB
> Gen:                 664
> THPeligible:           0
> VmFlags: rd wr mr mw me ac
> 70dd7000-71090000 rw-p 00000000 00:00 0                                  [anon:dalvik-/system/framework/boot.art]
> Size:               2788 kB
> KernelPageSize:        4 kB
> MMUPageSize:           4 kB
> Rss:                2788 kB
> Pss:                 275 kB
> Pss_Dirty:           275 kB
> Shared_Clean:          0 kB
> Shared_Dirty:       2584 kB
> Private_Clean:         0 kB
> Private_Dirty:       204 kB
> Referenced:         2716 kB
> Anonymous:          2788 kB
> KSM:                   0 kB
> LazyFree:              0 kB
> AnonHugePages:         0 kB
> ShmemPmdMapped:        0 kB
> FilePmdMapped:         0 kB
> Shared_Hugetlb:        0 kB
> Private_Hugetlb:       0 kB
> Swap:                  0 kB
> SwapPss:               0 kB
> Locked:                0 kB
> Gen:                1394
> THPeligible:           0
>
> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
> ---
>  fs/proc/task_mmu.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index f8d35f993fe5..9731f43aa639 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -408,12 +408,23 @@ struct mem_size_stats {
>         u64 pss_dirty;
>         u64 pss_locked;
>         u64 swap_pss;
> +#ifdef CONFIG_LRU_GEN
> +       u64 gen;
> +#endif
>  };
>
>  static void smaps_page_accumulate(struct mem_size_stats *mss,
>                 struct folio *folio, unsigned long size, unsigned long pss,
>                 bool dirty, bool locked, bool private)
>  {
> +#ifdef CONFIG_LRU_GEN
> +       int gen = folio_lru_gen(folio);
> +       struct lru_gen_folio *lrugen = &folio_lruvec(folio)->lrugen;
> +
> +       if (gen >= 0)
> +               mss->gen += (lru_gen_from_seq(lrugen->max_seq) - gen + MAX_NR_GENS) % MAX_NR_GENS;
> +#endif
> +
>         mss->pss += pss;
>
>         if (folio_test_anon(folio))
> @@ -852,6 +863,10 @@ static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss,
>         SEQ_PUT_DEC(" kB\nLocked:         ",
>                                         mss->pss_locked >> PSS_SHIFT);
>         seq_puts(m, " kB\n");
> +#ifdef CONFIG_LRU_GEN
> +       seq_put_decimal_ull_width(m, "Gen:            ",  mss->gen, 8);
> +       seq_puts(m, "\n");
> +#endif
>  }
>
>  static int show_smap(struct seq_file *m, void *v)
> --
> 2.25.1
>