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Message-ID: <87375y5xqq.fsf@yhuang-dev.intel.com>
Date: Wed, 01 Nov 2017 14:17:17 +0800
From: "Huang\, Ying" <ying.huang@...el.com>
To: Minchan Kim <minchan@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
Hugh Dickins <hughd@...gle.com>,
Huang Ying <ying.huang@...el.com>,
kernel-team <kernel-team@....com>
Subject: Re: [PATCH 2/2] mm:swap: unify cluster-based and vma-based swap readahead
Minchan Kim <minchan@...nel.org> writes:
> This patch makes do_swap_page no need to be aware of two different
> swap readahead algorithm. Just unify cluster-based and vma-based
> readahead function call.
>
> Signed-off-by: Minchan Kim <minchan@...nel.org>
> ---
> include/linux/swap.h | 17 ++++++++++++-----
> mm/memory.c | 11 ++++-------
> mm/shmem.c | 5 ++++-
> mm/swap_state.c | 21 +++++++++++++++------
> 4 files changed, 35 insertions(+), 19 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 7c7c8b344bc9..9cc330360eac 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -425,9 +425,11 @@ extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
> extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
> struct vm_area_struct *vma, unsigned long addr,
> bool *new_page_allocated);
> -extern struct page *swapin_readahead(swp_entry_t, gfp_t,
> - struct vm_area_struct *vma, unsigned long addr);
> -extern struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
> +extern struct page *cluster_readahead(swp_entry_t entry, gfp_t flag,
> + struct vm_fault *vmf);
In addition to swap readahead, there are file readahead too. So better
add swap in name, such as swap_cluster_readahead()?
> +extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
> + struct vm_fault *vmf);
> +extern struct page *vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
> struct vm_fault *vmf);
I don't find vma_readahead() is used outside of page_state.c, why
declare it here?
>
> /* linux/mm/swapfile.c */
> @@ -536,8 +538,13 @@ static inline void put_swap_page(struct page *page, swp_entry_t swp)
> {
> }
>
> +static inline struct page *cluster_readahead(swp_entry_t, gfp_t gfp_mask
> + struct vm_fault *vmf)
> +{
> +}
> +
> static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
> - struct vm_area_struct *vma, unsigned long addr)
> + struct vm_fault *vmf)
> {
> return NULL;
> }
> @@ -547,7 +554,7 @@ static inline bool swap_use_vma_readahead(void)
> return false;
> }
Now swap_use_vma_readahead() is used in swap_state.c only, so we can
remove it from the header file?
> -static inline struct page *do_swap_page_readahead(swp_entry_t fentry,
> +static inline struct page *vma_readahead(swp_entry_t fentry,
> gfp_t gfp_mask, struct vm_fault *vmf)
> {
> return NULL;
> diff --git a/mm/memory.c b/mm/memory.c
> index e955298e4290..ce5e3d7ccc5c 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2889,7 +2889,8 @@ int do_swap_page(struct vm_fault *vmf)
> if (si->flags & SWP_SYNCHRONOUS_IO &&
> __swap_count(si, entry) == 1) {
> /* skip swapcache */
> - page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
> + page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
> + vmf->address);
> if (page) {
> __SetPageLocked(page);
> __SetPageSwapBacked(page);
> @@ -2898,12 +2899,8 @@ int do_swap_page(struct vm_fault *vmf)
> swap_readpage(page, true);
> }
> } else {
> - if (swap_use_vma_readahead())
> - page = do_swap_page_readahead(entry,
> - GFP_HIGHUSER_MOVABLE, vmf);
> - else
> - page = swapin_readahead(entry,
> - GFP_HIGHUSER_MOVABLE, vma, vmf->address);
> + page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
> + vmf);
> swapcache = page;
> }
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 62dfdc097e44..2522bc0958e1 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1413,9 +1413,12 @@ static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
> {
> struct vm_area_struct pvma;
> struct page *page;
> + struct vm_fault vmf;
>
> shmem_pseudo_vma_init(&pvma, info, index);
> - page = swapin_readahead(swap, gfp, &pvma, 0);
> + vmf.vma = &pvma;
> + vmf.address = 0;
> + page = cluster_readahead(swap, gfp, &vmf);
> shmem_pseudo_vma_destroy(&pvma);
>
> return page;
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index e3c535fcd2df..5ee53d4ee047 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -538,11 +538,10 @@ static unsigned long swapin_nr_pages(unsigned long offset)
> }
>
> /**
> - * swapin_readahead - swap in pages in hope we need them soon
> + * cluster_readahead - swap in pages in hope we need them soon
> * @entry: swap entry of this memory
> * @gfp_mask: memory allocation flags
> - * @vma: user vma this address belongs to
> - * @addr: target address for mempolicy
> + * @vmf: fault information
> *
> * Returns the struct page for entry and addr, after queueing swapin.
> *
> @@ -556,8 +555,8 @@ static unsigned long swapin_nr_pages(unsigned long offset)
> *
> * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
> */
> -struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
> - struct vm_area_struct *vma, unsigned long addr)
> +struct page *cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
> + struct vm_fault *vmf)
> {
> struct page *page;
> unsigned long entry_offset = swp_offset(entry);
> @@ -566,6 +565,8 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
> unsigned long mask;
> struct blk_plug plug;
> bool do_poll = true, page_allocated;
> + struct vm_area_struct *vma = vmf->vma;
> + unsigned long addr = vmf->address;
>
> mask = swapin_nr_pages(offset) - 1;
> if (!mask)
> @@ -603,6 +604,14 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
> return read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll);
> }
>
No function document for swapin_readahead()? It is the main interface
for swap readahead.
> +struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
> + struct vm_fault *vmf)
> +{
> + return swap_use_vma_readahead() ?
> + vma_readahead(entry, gfp_mask, vmf) :
> + cluster_readahead(entry, gfp_mask, vmf);
> +}
> +
> int init_swap_address_space(unsigned int type, unsigned long nr_pages)
> {
> struct address_space *spaces, *space;
> @@ -719,7 +728,7 @@ static void swap_ra_info(struct vm_fault *vmf,
> pte_unmap(orig_pte);
> }
>
> -struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
> +struct page *vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
> struct vm_fault *vmf)
> {
> struct blk_plug plug;
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