On Sun, Nov 19, 2023 at 11:48 AM Kairui Song <ryncsn@xxxxxxxxx> wrote:
>
> From: Kairui Song <kasong@xxxxxxxxxxx>
>
> When a xa_value is returned by the cache lookup, keep it to be used
> later for workingset refault check instead of doing the looking up again
> in swapin_no_readahead.
>
> This does have a side effect of making swapoff also triggers workingset
> check, but should be fine since swapoff does effect the workload in many
> ways already.
I need to sleep on it a bit to see if this will create another problem or not.
>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
> ---
> mm/swap_state.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index e057c79fb06f..51de2a0412df 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -872,7 +872,6 @@ static struct page *swapin_no_readahead(swp_entry_t entry, gfp_t gfp_mask,
> {
> struct folio *folio;
> struct page *page;
> - void *shadow = NULL;
>
> page = alloc_pages_mpol(gfp_mask, 0, mpol, ilx, numa_node_id());
> folio = (struct folio *)page;
> @@ -888,10 +887,6 @@ static struct page *swapin_no_readahead(swp_entry_t entry, gfp_t gfp_mask,
>
> mem_cgroup_swapin_uncharge_swap(entry);
>
> - shadow = get_shadow_from_swap_cache(entry);
> - if (shadow)
> - workingset_refault(folio, shadow);
> -
> folio_add_lru(folio);
>
> /* To provide entry to swap_readpage() */
> @@ -922,11 +917,12 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
> enum swap_cache_result cache_result;
> struct swap_info_struct *si;
> struct mempolicy *mpol;
> + void *shadow = NULL;
> struct folio *folio;
> struct page *page;
> pgoff_t ilx;
>
> - folio = swap_cache_get_folio(entry, vmf, NULL);
> + folio = swap_cache_get_folio(entry, vmf, &shadow);
> if (folio) {
> page = folio_file_page(folio, swp_offset(entry));
> cache_result = SWAP_CACHE_HIT;
> @@ -938,6 +934,8 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
> if (swap_use_no_readahead(si, swp_offset(entry))) {
> page = swapin_no_readahead(entry, gfp_mask, mpol, ilx, vmf->vma->vm_mm);
> cache_result = SWAP_CACHE_BYPASS;
> + if (shadow)
> + workingset_refault(page_folio(page), shadow);
It is inconsistent why other flavors of readahead do not do the
workingset_refault here.
I suggest keeping the workingset_refault in swapin_no_readahead() and
pass the shadow argument in.
Chris
> } else if (swap_use_vma_readahead(si)) {
> page = swap_vma_readahead(entry, gfp_mask, mpol, ilx, vmf);
> cache_result = SWAP_CACHE_MISS;
> --
> 2.42.0
>
>
