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Tue, 09 Jan 2024 18:42:52 -0800 (PST) MIME-Version: 1.0 References: <20240102175338.62012-1-ryncsn@gmail.com> <20240102175338.62012-6-ryncsn@gmail.com> <8734vcb5nx.fsf@yhuang6-desk2.ccr.corp.intel.com> In-Reply-To: <8734vcb5nx.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Kairui Song Date: Wed, 10 Jan 2024 10:42:34 +0800 Message-ID: Subject: Re: [PATCH v2 5/9] mm/swap: introduce swapin_entry for unified readahead policy To: "Huang, Ying" Cc: linux-mm@kvack.org, Andrew Morton , Chris Li , Hugh Dickins , Johannes Weiner , Matthew Wilcox , Michal Hocko , Yosry Ahmed , David Hildenbrand , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 3BA4280004 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: pr5tt4qpedru6m6q37jyue59zyyjjrnt X-HE-Tag: 1704854573-992400 X-HE-Meta: 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 6Y++17d+ 0Thxsn6Rmmi6zgkNOjr9gLYWbuukCbaZXR5TVf1Oqv6ddxggL1PzC8HRhR+FnxAz57TjO2K9bMIg3ukqL2rNiyN7k31uSOjmtYGzgh0aD35EbYJbAeljlyIPMfobLpCVh1Q+GGnw4LZz6r2UOfuR+T+KcsQGcsoF7JBy2l1YAQwj5EIoOs+HyJ0j1IUdUmfUZU4CuV6nHhjoSBhfdzySUCf8hxr2B/HTjmqW0iCKFJLqn6g/7uvG/TqdNe67gFv7Otn+1GPGwrRNvUK3nQYccAM8OQaS/blDRr0IT91gF/pXDbs7Eclonb71MA8IjrcrHmEsEcXJWVasEoImdVPbhe28rngH8tZwEZkdVXxjx3dDkiY2UVJKrZHtezDk2uvaJ7nestEylePeXalY6tTSRydRGnpNfI3AaQgLP33bFo3g7GJNbmVM4p+8b0SZwLunJTWEYIQAwuFTZQLXuTNFJCZnt/qeHFGuDhW1oMIRHFbbQDvlR3350rPtyQfAkn6h/YNPMn1tIWdVzdO/ZYOvHaFe3fA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Huang, Ying =E4=BA=8E2024=E5=B9=B41=E6=9C=885=E6=97= =A5=E5=91=A8=E4=BA=94 15:30=E5=86=99=E9=81=93=EF=BC=9A > > Kairui Song writes: > > > From: Kairui Song > > > > Introduce swapin_entry which merges swapin_readahead and swapin_direct > > making it the main entry for swapin pages, and use a unified swapin > > policy. > > > > This commit makes swapoff make use of this new helper and now swapping > > off a 10G ZRAM (lzo-rle) is faster since readahead is skipped. > > > > Before: > > time swapoff /dev/zram0 > > real 0m12.337s > > user 0m0.001s > > sys 0m12.329s > > > > After: > > time swapoff /dev/zram0 > > real 0m9.728s > > user 0m0.001s > > sys 0m9.719s > > > > Signed-off-by: Kairui Song > > --- > > mm/memory.c | 21 +++++++-------------- > > mm/swap.h | 16 ++++------------ > > mm/swap_state.c | 49 +++++++++++++++++++++++++++++++++---------------- > > mm/swapfile.c | 7 ++----- > > 4 files changed, 46 insertions(+), 47 deletions(-) > > > > diff --git a/mm/memory.c b/mm/memory.c > > index 0165c8cad489..b56254a875f8 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -3801,6 +3801,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > > rmap_t rmap_flags =3D RMAP_NONE; > > bool exclusive =3D false; > > swp_entry_t entry; > > + bool swapcached; > > pte_t pte; > > vm_fault_t ret =3D 0; > > > > @@ -3864,21 +3865,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > > swapcache =3D folio; > > > > if (!folio) { > > - if (data_race(si->flags & SWP_SYNCHRONOUS_IO) && > > - __swap_count(entry) =3D=3D 1) { > > - /* skip swapcache and readahead */ > > - folio =3D swapin_direct(entry, GFP_HIGHUSER_MOVAB= LE, vmf); > > - if (folio) > > - page =3D &folio->page; > > + folio =3D swapin_entry(entry, GFP_HIGHUSER_MOVABLE, > > + vmf, &swapcached); > > + if (folio) { > > + page =3D folio_file_page(folio, swp_offset(entry)= ); > > + if (swapcached) > > + swapcache =3D folio; > > } else { > > - page =3D swapin_readahead(entry, GFP_HIGHUSER_MOV= ABLE, > > - vmf); > > - if (page) > > - folio =3D page_folio(page); > > - swapcache =3D folio; > > - } > > - > > - if (!folio) { > > /* > > * Back out if somebody else faulted in this pte > > * while we released the pte lock. > > diff --git a/mm/swap.h b/mm/swap.h > > index 83eab7b67e77..502a2801f817 100644 > > --- a/mm/swap.h > > +++ b/mm/swap.h > > @@ -54,10 +54,8 @@ struct folio *__read_swap_cache_async(swp_entry_t en= try, gfp_t gfp_flags, > > bool skip_if_exists); > > struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t flag, > > struct mempolicy *mpol, pgoff_t ilx); > > -struct page *swapin_readahead(swp_entry_t entry, gfp_t flag, > > - struct vm_fault *vmf); > > -struct folio *swapin_direct(swp_entry_t entry, gfp_t flag, > > - struct vm_fault *vmf); > > +struct folio *swapin_entry(swp_entry_t entry, gfp_t flag, > > + struct vm_fault *vmf, bool *swapcached); > > > > static inline unsigned int folio_swap_flags(struct folio *folio) > > { > > @@ -88,14 +86,8 @@ static inline struct folio *swap_cluster_readahead(s= wp_entry_t entry, > > return NULL; > > } > > > > -struct folio *swapin_direct(swp_entry_t entry, gfp_t flag, > > - struct vm_fault *vmf) > > -{ > > - return NULL; > > -} > > - > > -static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp= _mask, > > - struct vm_fault *vmf) > > +static inline struct folio *swapin_entry(swp_entry_t swp, gfp_t gfp_ma= sk, > > + struct vm_fault *vmf, bool *swapcached) > > { > > return NULL; > > } > > diff --git a/mm/swap_state.c b/mm/swap_state.c > > index d39c5369da21..66ff187aa5d3 100644 > > --- a/mm/swap_state.c > > +++ b/mm/swap_state.c > > @@ -316,6 +316,11 @@ void free_pages_and_swap_cache(struct encoded_page= **pages, int nr) > > release_pages(pages, nr); > > } > > > > +static inline bool swap_use_no_readahead(struct swap_info_struct *si, = swp_entry_t entry) > > +{ > > + return data_race(si->flags & SWP_SYNCHRONOUS_IO) && __swap_count(= entry) =3D=3D 1; > > +} > > + Hi Ying, Thanks for the review. > > It appears that there's only one caller of the function in the same > file? Why add a function? Later patch will extend the checker function. I can defer this change so it won't cause confusion for reviewers. > > > static inline bool swap_use_vma_readahead(void) > > { > > return READ_ONCE(enable_vma_readahead) && !atomic_read(&nr_rotate= _swap); > > @@ -870,8 +875,8 @@ static struct folio *swap_vma_readahead(swp_entry_t= targ_entry, gfp_t gfp_mask, > > * Returns the struct folio for entry and addr after the swap entry is= read > > * in. > > */ > > -struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask, > > - struct vm_fault *vmf) > > +static struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask, > > + struct vm_fault *vmf) > > { > > struct vm_area_struct *vma =3D vmf->vma; > > struct folio *folio; > > @@ -908,33 +913,45 @@ struct folio *swapin_direct(swp_entry_t entry, gf= p_t gfp_mask, > > } > > > > /** > > - * swapin_readahead - swap in pages in hope we need them soon > > + * swapin_entry - swap in a page from swap entry > > * @entry: swap entry of this memory > > * @gfp_mask: memory allocation flags > > * @vmf: fault information > > + * @swapcached: pointer to a bool used as indicator if the > > + * page is swapped in through swapcache. > > * > > * Returns the struct page for entry and addr, after queueing swapin. > > * > > - * It's a main entry function for swap readahead. By the configuration= , > > + * It's a main entry function for swap in. By the configuration, > > * it will read ahead blocks by cluster-based(ie, physical disk based) > > - * or vma-based(ie, virtual address based on faulty address) readahead= . > > + * or vma-based(ie, virtual address based on faulty address) readahead= , > > + * or skip the readahead (ie, ramdisk based swap device). > > */ > > -struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, > > - struct vm_fault *vmf) > > +struct folio *swapin_entry(swp_entry_t entry, gfp_t gfp_mask, > > + struct vm_fault *vmf, bool *swapcached) > > May be better to use > > struct folio *swapin_entry(swp_entry_t entry, gfp_t gfp_mask, > struct vm_fault *vmf, struct folio **swapcache= ) > > In this way, we can reduce the number of source lines in the caller. Following commit will rewrite this part to return a enum instead of bool, so this is just a intermediate change. And do_swap_page is the only caller that can benefit from this, not helpful for swapoff/shmem. I think we can just keep it this way here.