| Message ID | 20200922020148.3261797-2-riel@surriel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm,swap: skip swap readahead for instant IO (like zswap) | expand |
On Mon, Sep 21, 2020 at 10:01:47PM -0400, Rik van Riel wrote: > +static struct page *swap_cluster_read_one(swp_entry_t entry, > + unsigned long offset, gfp_t gfp_mask, > + struct vm_area_struct *vma, unsigned long addr, bool readahead) > +{ > + bool page_allocated; > + struct page *page; > + > + page =__read_swap_cache_async(swp_entry(swp_type(entry), offset), > + gfp_mask, vma, addr, &page_allocated); Missing whitespace after the "=". > + if (!page) > + return NULL; > + if (page_allocated) { > + swap_readpage(page, false); > + if (readahead) { > + SetPageReadahead(page); > + count_vm_event(SWAP_RA); > + } > + } > + put_page(page); > + return page; > +} I think swap_vma_readahead can be switched to your new helper pretty trivially as well, as could many of the users of read_swap_cache_async.
On Wed, 23 Sep 2020 07:32:43 +0100 Christoph Hellwig wrote: > On Mon, Sep 21, 2020 at 10:01:47PM -0400, Rik van Riel wrote: > > +static struct page *swap_cluster_read_one(swp_entry_t entry, > > + unsigned long offset, gfp_t gfp_mask, > > + struct vm_area_struct *vma, unsigned long addr, bool readahead) > > +{ > > + bool page_allocated; > > + struct page *page; > > + > > + page =__read_swap_cache_async(swp_entry(swp_type(entry), offset), > > + gfp_mask, vma, addr, &page_allocated); > > Missing whitespace after the "=". > > > + if (!page) > > + return NULL; > > + if (page_allocated) { > > + swap_readpage(page, false); > > + if (readahead) { > > + SetPageReadahead(page); > > + count_vm_event(SWAP_RA); > > + } > > + } > > + put_page(page); > > + return page; > > +} Check if put_page() makes page a hot potato at the call site on the v2 spin. > > I think swap_vma_readahead can be switched to your new helper > pretty trivially as well, as could many of the users of > read_swap_cache_async.
diff --git a/mm/swap_state.c b/mm/swap_state.c index c16eebb81d8b..aacb9ba53f63 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -594,6 +594,28 @@ static unsigned long swapin_nr_pages(unsigned long offset) return pages; } +static struct page *swap_cluster_read_one(swp_entry_t entry, + unsigned long offset, gfp_t gfp_mask, + struct vm_area_struct *vma, unsigned long addr, bool readahead) +{ + bool page_allocated; + struct page *page; + + page =__read_swap_cache_async(swp_entry(swp_type(entry), offset), + gfp_mask, vma, addr, &page_allocated); + if (!page) + return NULL; + if (page_allocated) { + swap_readpage(page, false); + if (readahead) { + SetPageReadahead(page); + count_vm_event(SWAP_RA); + } + } + put_page(page); + return page; +} + /** * swap_cluster_readahead - swap in pages in hope we need them soon * @entry: swap entry of this memory @@ -615,14 +637,13 @@ static unsigned long swapin_nr_pages(unsigned long offset) struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, struct vm_fault *vmf) { - struct page *page; unsigned long entry_offset = swp_offset(entry); unsigned long offset = entry_offset; unsigned long start_offset, end_offset; unsigned long mask; struct swap_info_struct *si = swp_swap_info(entry); struct blk_plug plug; - bool do_poll = true, page_allocated; + bool do_poll = true; struct vm_area_struct *vma = vmf->vma; unsigned long addr = vmf->address; @@ -649,19 +670,8 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, blk_start_plug(&plug); for (offset = start_offset; offset <= end_offset ; offset++) { /* Ok, do the async read-ahead now */ - page = __read_swap_cache_async( - swp_entry(swp_type(entry), offset), - gfp_mask, vma, addr, &page_allocated); - if (!page) - continue; - if (page_allocated) { - swap_readpage(page, false); - if (offset != entry_offset) { - SetPageReadahead(page); - count_vm_event(SWAP_RA); - } - } - put_page(page); + swap_cluster_read_one(entry, offset, gfp_mask, vma, addr, + offset != entry_offset); } blk_finish_plug(&plug);
Split swap single page readahead into its own function, to make the next patch easier to read. No functional changes. Signed-off-by: Rik van Riel <riel@surriel.com> --- mm/swap_state.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-)