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[2a03:2880:ff:3::face:b00c]) by smtp.gmail.com with ESMTPSA id l11-20020a633e0b000000b0045ff216a0casm1852791pga.3.2023.02.03.11.04.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Feb 2023 11:04:14 -0800 (PST) From: Nhat Pham To: akpm@linux-foundation.org Cc: hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bfoster@redhat.com, willy@infradead.org, linux-api@vger.kernel.org, kernel-team@meta.com Subject: [PATCH v9 1/3] workingset: refactor LRU refault to expose refault recency check Date: Fri, 3 Feb 2023 11:04:11 -0800 Message-Id: <20230203190413.2559707-2-nphamcs@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230203190413.2559707-1-nphamcs@gmail.com> References: <20230203190413.2559707-1-nphamcs@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756837983956690143?= X-GMAIL-MSGID: =?utf-8?q?1756837983956690143?= In preparation for computing recently evicted pages in cachestat, refactor workingset_refault and lru_gen_refault to expose a helper function that would test if an evicted page is recently evicted. Signed-off-by: Nhat Pham --- include/linux/swap.h | 1 + mm/workingset.c | 142 +++++++++++++++++++++++++++++-------------- 2 files changed, 97 insertions(+), 46 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index a18cf4b7c724..dae6f6f955eb 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -361,6 +361,7 @@ static inline void folio_set_swap_entry(struct folio *folio, swp_entry_t entry) } /* linux/mm/workingset.c */ +bool workingset_test_recent(void *shadow, bool file, bool *workingset); void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages); void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg); void workingset_refault(struct folio *folio, void *shadow); diff --git a/mm/workingset.c b/mm/workingset.c index 79585d55c45d..5f1d20a0a2fd 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -244,6 +244,30 @@ static void *lru_gen_eviction(struct folio *folio) return pack_shadow(mem_cgroup_id(memcg), pgdat, token, refs); } +/* + * Test if the folio is recently evicted. + * + * As a side effect, also populates the references with + * values unpacked from the shadow of the evicted folio. + */ +static bool lru_gen_test_recent(void *shadow, bool file, int *memcgid, + struct pglist_data **pgdat, unsigned long *token, bool *workingset) +{ + struct mem_cgroup *eviction_memcg; + struct lruvec *lruvec; + struct lru_gen_struct *lrugen; + unsigned long min_seq; + + unpack_shadow(shadow, memcgid, pgdat, token, workingset); + eviction_memcg = mem_cgroup_from_id(*memcgid); + + lruvec = mem_cgroup_lruvec(eviction_memcg, *pgdat); + lrugen = &lruvec->lrugen; + + min_seq = READ_ONCE(lrugen->min_seq[file]); + return (*token >> LRU_REFS_WIDTH) == (min_seq & (EVICTION_MASK >> LRU_REFS_WIDTH)); +} + static void lru_gen_refault(struct folio *folio, void *shadow) { int hist, tier, refs; @@ -258,23 +282,22 @@ static void lru_gen_refault(struct folio *folio, void *shadow) int type = folio_is_file_lru(folio); int delta = folio_nr_pages(folio); - unpack_shadow(shadow, &memcg_id, &pgdat, &token, &workingset); - - if (pgdat != folio_pgdat(folio)) - return; - rcu_read_lock(); + if (!lru_gen_test_recent(shadow, type, &memcg_id, &pgdat, &token, + &workingset)) + goto unlock; + memcg = folio_memcg_rcu(folio); if (memcg_id != mem_cgroup_id(memcg)) goto unlock; + if (pgdat != folio_pgdat(folio)) + return; + lruvec = mem_cgroup_lruvec(memcg, pgdat); lrugen = &lruvec->lrugen; - min_seq = READ_ONCE(lrugen->min_seq[type]); - if ((token >> LRU_REFS_WIDTH) != (min_seq & (EVICTION_MASK >> LRU_REFS_WIDTH))) - goto unlock; hist = lru_hist_from_seq(min_seq); /* see the comment in folio_lru_refs() */ @@ -306,6 +329,12 @@ static void *lru_gen_eviction(struct folio *folio) return NULL; } +static bool lru_gen_test_recent(void *shadow, bool file, int *memcgid, + struct pglist_data **pgdat, unsigned long *token, bool *workingset) +{ + return false; +} + static void lru_gen_refault(struct folio *folio, void *shadow) { } @@ -373,40 +402,31 @@ void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg) folio_test_workingset(folio)); } -/** - * workingset_refault - Evaluate the refault of a previously evicted folio. - * @folio: The freshly allocated replacement folio. - * @shadow: Shadow entry of the evicted folio. +/* + * Test if the folio is recently evicted by checking if + * refault distance of shadow exceeds workingset size. * - * Calculates and evaluates the refault distance of the previously - * evicted folio in the context of the node and the memcg whose memory - * pressure caused the eviction. + * As a side effect, populate workingset with the value + * unpacked from shadow. */ -void workingset_refault(struct folio *folio, void *shadow) +bool workingset_test_recent(void *shadow, bool file, bool *workingset) { - bool file = folio_is_file_lru(folio); struct mem_cgroup *eviction_memcg; struct lruvec *eviction_lruvec; unsigned long refault_distance; unsigned long workingset_size; - struct pglist_data *pgdat; - struct mem_cgroup *memcg; - unsigned long eviction; - struct lruvec *lruvec; unsigned long refault; - bool workingset; int memcgid; - long nr; + struct pglist_data *pgdat; + unsigned long eviction; - if (lru_gen_enabled()) { - lru_gen_refault(folio, shadow); - return; - } + if (lru_gen_enabled()) + return lru_gen_test_recent(shadow, file, &memcgid, &pgdat, &eviction, + workingset); - unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset); + unpack_shadow(shadow, &memcgid, &pgdat, &eviction, workingset); eviction <<= bucket_order; - rcu_read_lock(); /* * Look up the memcg associated with the stored ID. It might * have been deleted since the folio's eviction. @@ -425,7 +445,8 @@ void workingset_refault(struct folio *folio, void *shadow) */ eviction_memcg = mem_cgroup_from_id(memcgid); if (!mem_cgroup_disabled() && !eviction_memcg) - goto out; + return false; + eviction_lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat); refault = atomic_long_read(&eviction_lruvec->nonresident_age); @@ -447,21 +468,6 @@ void workingset_refault(struct folio *folio, void *shadow) */ refault_distance = (refault - eviction) & EVICTION_MASK; - /* - * The activation decision for this folio is made at the level - * where the eviction occurred, as that is where the LRU order - * during folio reclaim is being determined. - * - * However, the cgroup that will own the folio is the one that - * is actually experiencing the refault event. - */ - nr = folio_nr_pages(folio); - memcg = folio_memcg(folio); - pgdat = folio_pgdat(folio); - lruvec = mem_cgroup_lruvec(memcg, pgdat); - - mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr); - mem_cgroup_flush_stats_delayed(); /* * Compare the distance to the existing workingset size. We @@ -483,7 +489,51 @@ void workingset_refault(struct folio *folio, void *shadow) NR_INACTIVE_ANON); } } - if (refault_distance > workingset_size) + + return refault_distance <= workingset_size; +} + +/** + * workingset_refault - Evaluate the refault of a previously evicted folio. + * @folio: The freshly allocated replacement folio. + * @shadow: Shadow entry of the evicted folio. + * + * Calculates and evaluates the refault distance of the previously + * evicted folio in the context of the node and the memcg whose memory + * pressure caused the eviction. + */ +void workingset_refault(struct folio *folio, void *shadow) +{ + bool file = folio_is_file_lru(folio); + struct pglist_data *pgdat; + struct mem_cgroup *memcg; + struct lruvec *lruvec; + bool workingset; + long nr; + + if (lru_gen_enabled()) { + lru_gen_refault(folio, shadow); + return; + } + + rcu_read_lock(); + + /* + * The activation decision for this folio is made at the level + * where the eviction occurred, as that is where the LRU order + * during folio reclaim is being determined. + * + * However, the cgroup that will own the folio is the one that + * is actually experiencing the refault event. + */ + nr = folio_nr_pages(folio); + memcg = folio_memcg(folio); + pgdat = folio_pgdat(folio); + lruvec = mem_cgroup_lruvec(memcg, pgdat); + + mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr); + + if (!workingset_test_recent(shadow, file, &workingset)) goto out; folio_set_active(folio); From patchwork Fri Feb 3 19:04:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nhat Pham X-Patchwork-Id: 52615 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:eb09:0:0:0:0:0 with SMTP id s9csp1011668wrn; Fri, 3 Feb 2023 11:07:58 -0800 (PST) X-Google-Smtp-Source: AK7set/47Ky7tWz6+J1v8X+gCYSKKUPfyQs1mow0ORVpEfl93V446eHfzEzDuzigYDhs6M7+aOgM X-Received: by 2002:a17:903:2288:b0:198:dd3f:2847 with SMTP id b8-20020a170903228800b00198dd3f2847mr5040440plh.21.1675451278195; Fri, 03 Feb 2023 11:07:58 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1675451278; cv=none; d=google.com; s=arc-20160816; b=J9Q4V9a11KJEH1hQ2CIhOYPHobEVXNus4XonDgiIiXPZvvY1kCz8j+rRfjv6Roqfm+ zKzVU2svmohVODgCtvAQgNtJtFj/My/6cNimPafRntYzoIqvVX97ntDkKDt5zVLwbpXA CuhgXWMN5o6+pjIxCh4QHfxfjjJVvl4qwfIO4MUNUCsBr3m/Ue6f4NXwGhAybbatrZSR QJaHt3sRsQXlaQf7+IyWriZeU0UrURBG0uVeYHmiXrVARWCZswodeLYIYLlRu1Rw4X6J +PV5SCTMqKknBa6xdkD0rsb5WQdO5ANx5l0gzTn3GrAVTOOCNC5ypgtbEe+Ga68XFp7i zWtg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=gdtSVhY4zdAc2hQWqvswv4yZEjUGul2BnVrn+T/QrFo=; b=Fe1mI6ARC4Zy5sA1S7Ntt8/vJDp1WCSAZsJmZGMsCToGW6TYr6k9VBjzifc+DBFhyK S06YrNfq8c6BoGltKFk+TrxS1Su37EPmW9HplgXqhwY8lMueMekyw3caoEOYeTNezB/3 jt+TRM8nP/0mvZFZxOtXko3r9o0FjSgbrDF8eVgIBWzIfuLo3JbXIUhXC/LuONG9t2Ax iW4jxiPxTD/fGWk4QCj9XfDgTdwZnwsxBybc7yNsJjmDeU9Et7/RH4uAX3qupV86cyKl EGG/jQaG35MUA1LYIcBr0Y98UrBfhgPvoyBY2h21Pg/RTHHc4d62MQF2skJhS2GKFc4v Za9g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=EycmqHCj; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from out1.vger.email (out1.vger.email. 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[2a03:2880:ff:16::face:b00c]) by smtp.gmail.com with ESMTPSA id a17-20020a170902ee9100b00194b0074b25sm1941775pld.160.2023.02.03.11.04.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Feb 2023 11:04:15 -0800 (PST) From: Nhat Pham To: akpm@linux-foundation.org Cc: hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bfoster@redhat.com, willy@infradead.org, linux-api@vger.kernel.org, kernel-team@meta.com Subject: [PATCH v9 2/3] cachestat: implement cachestat syscall Date: Fri, 3 Feb 2023 11:04:12 -0800 Message-Id: <20230203190413.2559707-3-nphamcs@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230203190413.2559707-1-nphamcs@gmail.com> References: <20230203190413.2559707-1-nphamcs@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756837999245946634?= X-GMAIL-MSGID: =?utf-8?q?1756837999245946634?= There is currently no good way to query the page cache state of large file sets and directory trees. There is mincore(), but it scales poorly: the kernel writes out a lot of bitmap data that userspace has to aggregate, when the user really doesn not care about per-page information in that case. The user also needs to mmap and unmap each file as it goes along, which can be quite slow as well. This patch implements a new syscall that queries cache state of a file and summarizes the number of cached pages, number of dirty pages, number of pages marked for writeback, number of (recently) evicted pages, etc. in a given range. Currently, the syscall is only wired in for x86 architecture. NAME cachestat - query the page cache statistics of a file. SYNOPSIS #include struct cachestat { __u64 nr_cache; __u64 nr_dirty; __u64 nr_writeback; __u64 nr_evicted; __u64 nr_recently_evicted; }; int cachestat(unsigned int fd, loff_t off, size_t len, struct cachestat *cstat, unsigned int flags); DESCRIPTION cachestat() queries the number of cached pages, number of dirty pages, number of pages marked for writeback, number of evicted pages, number of recently evicted pages, in the bytes range given by `off` and `len`. An evicted page is a page that is previously in the page cache but has been evicted since. A page is recently evicted if its last eviction was recent enough that its reentry to the cache would indicate that it is actively being used by the system, and that there is memory pressure on the system. These values are returned in a cachestat struct, whose address is given by the `cstat` argument. The `off` and `len` arguments must be non-negative integers. If `len` > 0, the queried range is [`off`, `off` + `len`]. If `len` == 0, we will query in the range from `off` to the end of the file. The `flags` argument is unused for now, but is included for future extensibility. User should pass 0 (i.e no flag specified). RETURN VALUE On success, cachestat returns 0. On error, -1 is returned, and errno is set to indicate the error. ERRORS EFAULT cstat points to an invalid address. EINVAL invalid offset or flags. EBADF invalid file descriptor. Signed-off-by: Nhat Pham --- arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + include/linux/compat.h | 4 +- include/linux/fs.h | 3 + include/linux/syscalls.h | 4 + include/uapi/asm-generic/unistd.h | 5 +- include/uapi/linux/mman.h | 9 ++ init/Kconfig | 10 ++ kernel/sys_ni.c | 1 + mm/filemap.c | 157 +++++++++++++++++++++++++ 10 files changed, 193 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 320480a8db4f..01d1cc009250 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -455,3 +455,4 @@ 448 i386 process_mrelease sys_process_mrelease 449 i386 futex_waitv sys_futex_waitv 450 i386 set_mempolicy_home_node sys_set_mempolicy_home_node +451 i386 cachestat sys_cachestat compat_sys_cachestat diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index c84d12608cd2..227538b0ce80 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -372,6 +372,7 @@ 448 common process_mrelease sys_process_mrelease 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node +451 common cachestat sys_cachestat # # Due to a historical design error, certain syscalls are numbered differently diff --git a/include/linux/compat.h b/include/linux/compat.h index 594357881b0b..353d3ce657a7 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -816,7 +816,9 @@ asmlinkage long compat_sys_sendmsg(int fd, struct compat_msghdr __user *msg, asmlinkage long compat_sys_recvmsg(int fd, struct compat_msghdr __user *msg, unsigned int flags); -/* mm/filemap.c: No generic prototype for readahead */ +/* mm/filemap.c */ +asmlinkage long compat_sys_cachestat(int fd, compat_arg_u64(off), + size_t len, struct cachestat __user *cstat, unsigned int flags); /* security/keys/keyctl.c */ asmlinkage long compat_sys_keyctl(u32 option, diff --git a/include/linux/fs.h b/include/linux/fs.h index e654435f1651..83300f1491e7 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -75,6 +75,7 @@ struct fs_context; struct fs_parameter_spec; struct fileattr; struct iomap_ops; +struct cachestat; extern void __init inode_init(void); extern void __init inode_init_early(void); @@ -830,6 +831,8 @@ void filemap_invalidate_lock_two(struct address_space *mapping1, struct address_space *mapping2); void filemap_invalidate_unlock_two(struct address_space *mapping1, struct address_space *mapping2); +void filemap_cachestat(struct address_space *mapping, pgoff_t first_index, + pgoff_t last_index, struct cachestat *cs); /* diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index a34b0f9a9972..f92f25d96286 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -72,6 +72,7 @@ struct open_how; struct mount_attr; struct landlock_ruleset_attr; enum landlock_rule_type; +struct cachestat; #include #include @@ -1056,6 +1057,9 @@ asmlinkage long sys_memfd_secret(unsigned int flags); asmlinkage long sys_set_mempolicy_home_node(unsigned long start, unsigned long len, unsigned long home_node, unsigned long flags); +asmlinkage long sys_cachestat(unsigned int fd, unsigned long off_low, + unsigned long off_high, size_t len, struct cachestat __user *cstat, + unsigned int flags); /* * Architecture-specific system calls diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index 45fa180cc56a..dc5fcfee7f09 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -886,8 +886,11 @@ __SYSCALL(__NR_futex_waitv, sys_futex_waitv) #define __NR_set_mempolicy_home_node 450 __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node) +#define __NR_cachestat 451 +__SC_COMP(__NR_cachestat, sys_cachestat, compat_sys_cachestat) + #undef __NR_syscalls -#define __NR_syscalls 451 +#define __NR_syscalls 452 /* * 32 bit systems traditionally used different diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h index f55bc680b5b0..fe03ed0b7587 100644 --- a/include/uapi/linux/mman.h +++ b/include/uapi/linux/mman.h @@ -4,6 +4,7 @@ #include #include +#include #define MREMAP_MAYMOVE 1 #define MREMAP_FIXED 2 @@ -41,4 +42,12 @@ #define MAP_HUGE_2GB HUGETLB_FLAG_ENCODE_2GB #define MAP_HUGE_16GB HUGETLB_FLAG_ENCODE_16GB +struct cachestat { + __u64 nr_cache; + __u64 nr_dirty; + __u64 nr_writeback; + __u64 nr_evicted; + __u64 nr_recently_evicted; +}; + #endif /* _UAPI_LINUX_MMAN_H */ diff --git a/init/Kconfig b/init/Kconfig index 694f7c160c9c..da96ac29af1d 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1798,6 +1798,16 @@ config RSEQ If unsure, say Y. +config CACHESTAT_SYSCALL + bool "Enable cachestat() system call" if EXPERT + default y + help + Enable the cachestat system call, which queries the page cache + statistics of a file (number of cached pages, dirty pages, + pages marked for writeback, (recently) evicted pages). + + If unsure say Y here. + config DEBUG_RSEQ default n bool "Enabled debugging of rseq() system call" if EXPERT diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 860b2dcf3ac4..04bfb1e4d377 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -299,6 +299,7 @@ COND_SYSCALL(set_mempolicy); COND_SYSCALL(migrate_pages); COND_SYSCALL(move_pages); COND_SYSCALL(set_mempolicy_home_node); +COND_SYSCALL(cachestat); COND_SYSCALL(perf_event_open); COND_SYSCALL(accept4); diff --git a/mm/filemap.c b/mm/filemap.c index 08341616ae7a..87a391976408 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -55,6 +56,9 @@ #include /* for try_to_free_buffers */ #include +#include + +#include "swap.h" /* * Shared mappings implemented 30.11.1994. It's not fully working yet, @@ -3949,3 +3953,156 @@ bool filemap_release_folio(struct folio *folio, gfp_t gfp) return try_to_free_buffers(folio); } EXPORT_SYMBOL(filemap_release_folio); + +/** + * filemap_cachestat() - compute the page cache statistics of a mapping + * @mapping: The mapping to compute the statistics for. + * @first_index: The starting page cache index. + * @last_index: The final page index (inclusive). + * @cs: the cachestat struct to write the result to. + * + * This will query the page cache statistics of a mapping in the + * page range of [first_index, last_index] (inclusive). The statistics + * queried include: number of dirty pages, number of pages marked for + * writeback, and the number of (recently) evicted pages. + */ +void filemap_cachestat(struct address_space *mapping, pgoff_t first_index, + pgoff_t last_index, struct cachestat *cs) +{ + XA_STATE(xas, &mapping->i_pages, first_index); + struct folio *folio; + + rcu_read_lock(); + xas_for_each(&xas, folio, last_index) { + unsigned long nr_pages; + pgoff_t folio_first_index, folio_last_index; + + if (xas_retry(&xas, folio)) + continue; + + nr_pages = folio_nr_pages(folio); + folio_first_index = folio_pgoff(folio); + folio_last_index = folio_first_index + nr_pages - 1; + + /* Folios might straddle the range boundaries, only count covered subpages */ + if (folio_first_index < first_index) + nr_pages -= first_index - folio_first_index; + + if (folio_last_index > last_index) + nr_pages -= folio_last_index - last_index; + + if (xa_is_value(folio)) { + /* page is evicted */ + void *shadow = (void *)folio; + bool workingset; /* not used */ + + cs->nr_evicted += nr_pages; + +#ifdef CONFIG_SWAP /* implies CONFIG_MMU */ + if (shmem_mapping(mapping)) { + /* shmem file - in swap cache */ + swp_entry_t swp = radix_to_swp_entry(folio); + + shadow = get_shadow_from_swap_cache(swp); + } +#endif + if (workingset_test_recent(shadow, true, &workingset)) + cs->nr_recently_evicted += nr_pages; + + goto resched; + } + + /* page is in cache */ + cs->nr_cache += nr_pages; + + if (folio_test_dirty(folio)) + cs->nr_dirty += nr_pages; + + if (folio_test_writeback(folio)) + cs->nr_writeback += nr_pages; + +resched: + if (need_resched()) { + xas_pause(&xas); + cond_resched_rcu(); + } + } + rcu_read_unlock(); +} +EXPORT_SYMBOL(filemap_cachestat); + +#ifdef CONFIG_CACHESTAT_SYSCALL +long ksys_cachestat(unsigned int fd, loff_t off, size_t len, + struct cachestat __user *cstat, unsigned int flags) +{ + struct fd f = fdget(fd); + struct address_space *mapping; + struct cachestat cs; + pgoff_t first_index = off >> PAGE_SHIFT; + pgoff_t last_index = + len == 0 ? ULONG_MAX : (off + len - 1) >> PAGE_SHIFT; + + if (!f.file) + return -EBADF; + + if (off < 0 || flags != 0) { + fdput(f); + return -EINVAL; + } + + memset(&cs, 0, sizeof(struct cachestat)); + mapping = f.file->f_mapping; + filemap_cachestat(mapping, first_index, last_index, &cs); + fdput(f); + + if (copy_to_user(cstat, &cs, sizeof(struct cachestat))) + return -EFAULT; + + return 0; +} + +/* + * The cachestat(5) system call. + * + * cachestat() returns the page cache statistics of a file in the + * bytes range specified by `off` and `len`: number of cached pages, + * number of dirty pages, number of pages marked for writeback, + * number of evicted pages, and number of recently evicted pages. + * + * An evicted page is a page that is previously in the page cache + * but has been evicted since. A page is recently evicted if its last + * eviction was recent enough that its reentry to the cache would + * indicate that it is actively being used by the system, and that + * there is memory pressure on the system. + * + * `off` and `len` must be non-negative integers. If `len` > 0, + * the queried range is [`off`, `off` + `len`]. If `len` == 0, + * we will query in the range from `off` to the end of the file. + * + * The `flags` argument is unused for now, but is included for future + * extensibility. User should pass 0 (i.e no flag specified). + * + * Because the status of a page can change after cachestat() checks it + * but before it returns to the application, the returned values may + * contain stale information. + * + * return values: + * zero - success + * -EFAULT - cstat points to an illegal address + * -EINVAL - invalid arguments + * -EBADF - invalid file descriptor + */ +SYSCALL_DEFINE5(cachestat, unsigned int, fd, loff_t, off, size_t, len, + struct cachestat __user *, cstat, unsigned int, flags) +{ + return ksys_cachestat(fd, off, len, cstat, flags); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE6(cachestat, unsigned int, fd, compat_arg_u64_dual(off), + size_t, len, struct cachestat __user *, cstat, unsigned int, flags) +{ + return ksys_cachestat(fd, compat_arg_u64_glue(off), len, cstat, flags); +} +#endif +#endif /* CONFIG_CACHESTAT_SYSCALL */ From patchwork Fri Feb 3 19:04:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nhat Pham X-Patchwork-Id: 52616 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:eb09:0:0:0:0:0 with SMTP id s9csp1011689wrn; Fri, 3 Feb 2023 11:08:00 -0800 (PST) X-Google-Smtp-Source: AK7set/KLYd2Pk1oq0wBZL+IvqG2d/4zCCPfkIqvUfdEmh2C/I+AzPkCr9cO/26GpNcBxXBkUVIa X-Received: by 2002:a05:6a00:1626:b0:586:b33c:be2 with SMTP id e6-20020a056a00162600b00586b33c0be2mr9564740pfc.26.1675451280636; Fri, 03 Feb 2023 11:08:00 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1675451280; cv=none; d=google.com; s=arc-20160816; b=O3Glujaq9UDRvUKGwH48UDJh/JVCVW1qOynkbTRT8xMHLTCPaVziGY/ca7Oj1sZqS2 z0/B52AILf/bzdUeFu9WQFCf+rnYGGTeuek/LT7SkLO0nJlB+awFXk8v1lrO+JyLptV/ hpJHT/GnJm/+C2Fv0Eq0L5OLifabNxZYFBR7uJwgPfjYMe78RPFQpgPJQ+SJ1obkPNM5 6XYOk+0U9zpvNH2eftQnSgXKhENLCIlUDEWzatUHrk+/4XfKk4EQ5VoG92/uilqkdbf2 4O5lP+/2kqqs5Nx4Eq3eN3C2ifRmvzoaPldBzdf3yUnjtpjCriyW+NBprUESVnwth6dX V7uQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=xv2Em6KNiGaU6QjEB8S2E3cr0KOpR5Jc9laazewASFk=; b=osgxOMa6O/ud/rS2JmxqKTKDPX+1+XF/I7Usr3ZJGldKkqx3osA9CHS96I9fFYieN2 OEzdbSr1uMdmWUh5x6Fznf6GEbsTnV9wc9QmvgiTxyxHH+AICgTjccWXcuRKiGlc9X63 FETuFpQ0KLn8UHiwacrCuc+uS5XYbejwHrO+tg9yRpuhy95xHKHB8WP0sjb3xsAYlob3 95A7S2d1+4WCVfoujztZRssHBFmXjetMRB4cA5Gf03MchCOdIJM3ZuunoQvfhaF8kb6i toYQCwr+Qh652bLOfPCgW5Icern1M01yOUfZ6DvYF1hT/36R+JngB0DmuSlrJPRRFSvX 4otQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=HwyZleEv; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from out1.vger.email (out1.vger.email. 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[2a03:2880:ff:2::face:b00c]) by smtp.gmail.com with ESMTPSA id v12-20020a17090a0c8c00b0022be7a9e196sm5331387pja.1.2023.02.03.11.04.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Feb 2023 11:04:16 -0800 (PST) From: Nhat Pham To: akpm@linux-foundation.org Cc: hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bfoster@redhat.com, willy@infradead.org, linux-api@vger.kernel.org, kernel-team@meta.com Subject: [PATCH v9 3/3] selftests: Add selftests for cachestat Date: Fri, 3 Feb 2023 11:04:13 -0800 Message-Id: <20230203190413.2559707-4-nphamcs@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230203190413.2559707-1-nphamcs@gmail.com> References: <20230203190413.2559707-1-nphamcs@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756838002287092993?= X-GMAIL-MSGID: =?utf-8?q?1756838002287092993?= Test cachestat on a newly created file, /dev/ files, and /proc/ files. Also test on a shmem file (which can also be tested with huge pages since tmpfs supports huge pages). Signed-off-by: Nhat Pham --- MAINTAINERS | 7 + tools/testing/selftests/Makefile | 1 + tools/testing/selftests/cachestat/.gitignore | 2 + tools/testing/selftests/cachestat/Makefile | 8 + .../selftests/cachestat/test_cachestat.c | 256 ++++++++++++++++++ 5 files changed, 274 insertions(+) create mode 100644 tools/testing/selftests/cachestat/.gitignore create mode 100644 tools/testing/selftests/cachestat/Makefile create mode 100644 tools/testing/selftests/cachestat/test_cachestat.c diff --git a/MAINTAINERS b/MAINTAINERS index a198da986146..792a866353ec 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -4552,6 +4552,13 @@ S: Supported F: Documentation/filesystems/caching/cachefiles.rst F: fs/cachefiles/ +CACHESTAT: PAGE CACHE STATS FOR A FILE +M: Nhat Pham +M: Johannes Weiner +L: linux-mm@kvack.org +S: Maintained +F: tools/testing/selftests/cachestat/test_cachestat.c + CADENCE MIPI-CSI2 BRIDGES M: Maxime Ripard L: linux-media@vger.kernel.org diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 0464b2c6c1e4..3cad0b38c5c2 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -4,6 +4,7 @@ TARGETS += amd-pstate TARGETS += arm64 TARGETS += bpf TARGETS += breakpoints +TARGETS += cachestat TARGETS += capabilities TARGETS += cgroup TARGETS += clone3 diff --git a/tools/testing/selftests/cachestat/.gitignore b/tools/testing/selftests/cachestat/.gitignore new file mode 100644 index 000000000000..d6c30b43a4bb --- /dev/null +++ b/tools/testing/selftests/cachestat/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +test_cachestat diff --git a/tools/testing/selftests/cachestat/Makefile b/tools/testing/selftests/cachestat/Makefile new file mode 100644 index 000000000000..fca73aaa7d14 --- /dev/null +++ b/tools/testing/selftests/cachestat/Makefile @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0 +TEST_GEN_PROGS := test_cachestat + +CFLAGS += $(KHDR_INCLUDES) +CFLAGS += -Wall +CFLAGS += -lrt + +include ../lib.mk diff --git a/tools/testing/selftests/cachestat/test_cachestat.c b/tools/testing/selftests/cachestat/test_cachestat.c new file mode 100644 index 000000000000..d44b6d435444 --- /dev/null +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -0,0 +1,256 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../kselftest.h" + +static const char * const dev_files[] = { + "/dev/zero", "/dev/null", "/dev/urandom", + "/proc/version", "/proc" +}; +static const int cachestat_nr = 451; + +void print_cachestat(struct cachestat *cs) +{ + ksft_print_msg( + "Using cachestat: Cached: %lu, Dirty: %lu, Writeback: %lu, Evicted: %lu, Recently Evicted: %lu\n", + cs->nr_cache, cs->nr_dirty, cs->nr_writeback, + cs->nr_evicted, cs->nr_recently_evicted); +} + +bool write_exactly(int fd, size_t filesize) +{ + char data[filesize]; + bool ret = true; + int random_fd = open("/dev/urandom", O_RDONLY); + + if (random_fd < 0) { + ksft_print_msg("Unable to access urandom.\n"); + ret = false; + goto out; + } else { + int remained = filesize; + char *cursor = data; + + while (remained) { + ssize_t read_len = read(random_fd, cursor, remained); + + if (read_len <= 0) { + ksft_print_msg("Unable to read from urandom.\n"); + ret = false; + goto close_random_fd; + } + + remained -= read_len; + cursor += read_len; + } + + /* write random data to fd */ + remained = filesize; + cursor = data; + while (remained) { + ssize_t write_len = write(fd, cursor, remained); + + if (write_len <= 0) { + ksft_print_msg("Unable write random data to file.\n"); + ret = false; + goto close_random_fd; + } + + remained -= write_len; + cursor += write_len; + } + } + +close_random_fd: + close(random_fd); +out: + return ret; +} + +/* + * Open/create the file at filename, (optionally) write random data to it + * (exactly num_pages), then test the cachestat syscall on this file. + * + * If test_fsync == true, fsync the file, then check the number of dirty + * pages. + */ +bool test_cachestat(const char *filename, bool write_random, bool create, + bool test_fsync, unsigned long num_pages, int open_flags, + mode_t open_mode) +{ + size_t PS = sysconf(_SC_PAGESIZE); + int filesize = num_pages * PS; + bool ret = true; + long syscall_ret; + struct cachestat cs; + + int fd = open(filename, open_flags, open_mode); + + if (fd == -1) { + ksft_print_msg("Unable to create/open file.\n"); + goto out; + } else { + ksft_print_msg("Create/open %s\n", filename); + } + + if (write_random) { + if (!write_exactly(fd, filesize)) { + ksft_print_msg("Unable to access urandom.\n"); + ret = false; + goto out1; + } + } + + syscall_ret = syscall(cachestat_nr, fd, 0, filesize, &cs, 0); + + ksft_print_msg("Cachestat call returned %ld\n", syscall_ret); + + if (syscall_ret) { + ksft_print_msg("Cachestat returned non-zero.\n"); + ret = false; + goto out1; + + } else { + print_cachestat(&cs); + + if (write_random) { + if (cs.nr_cache + cs.nr_evicted != num_pages) { + ksft_print_msg( + "Total number of cached and evicted pages is off.\n"); + ret = false; + } + } + } + + if (test_fsync) { + if (fsync(fd)) { + ksft_print_msg("fsync fails.\n"); + ret = false; + } else { + syscall_ret = syscall(cachestat_nr, fd, 0, filesize, &cs, 0); + + ksft_print_msg("Cachestat call (after fsync) returned %ld\n", + syscall_ret); + + if (!syscall_ret) { + print_cachestat(&cs); + + if (cs.nr_dirty) { + ret = false; + ksft_print_msg( + "Number of dirty should be zero after fsync.\n"); + } + } else { + ksft_print_msg("Cachestat (after fsync) returned non-zero.\n"); + ret = false; + goto out1; + } + } + } + +out1: + close(fd); + + if (create) + remove(filename); +out: + return ret; +} + +bool test_cachestat_shmem(void) +{ + size_t PS = sysconf(_SC_PAGESIZE); + size_t filesize = PS * 512 * 2; /* 2 2MB huge pages */ + int syscall_ret; + off_t off = PS; + size_t compute_len = PS * 512; + char *filename = "tmpshmcstat"; + struct cachestat cs; + bool ret = true; + unsigned long num_pages = compute_len / PS; + int fd = shm_open(filename, O_CREAT | O_RDWR, 0600); + + if (fd < 0) { + ksft_print_msg("Unable to create shmem file.\n"); + ret = false; + goto out; + } + + if (ftruncate(fd, filesize)) { + ksft_print_msg("Unable to trucate shmem file.\n"); + ret = false; + goto close_fd; + } + + if (!write_exactly(fd, filesize)) { + ksft_print_msg("Unable to write to shmem file.\n"); + ret = false; + goto close_fd; + } + + syscall_ret = syscall(cachestat_nr, fd, off, compute_len, &cs, 0); + + if (syscall_ret) { + ksft_print_msg("Cachestat returned non-zero.\n"); + ret = false; + goto close_fd; + } else { + print_cachestat(&cs); + if (cs.nr_cache + cs.nr_evicted != num_pages) { + ksft_print_msg( + "Total number of cached and evicted pages is off.\n"); + ret = false; + } + } + +close_fd: + shm_unlink(filename); +out: + return ret; +} + +int main(void) +{ + int ret = 0; + + for (int i = 0; i < 5; i++) { + const char *dev_filename = dev_files[i]; + + if (test_cachestat(dev_filename, false, false, false, + 4, O_RDONLY, 0400)) + ksft_test_result_pass("cachestat works with %s\n", dev_filename); + else { + ksft_test_result_fail("cachestat fails with %s\n", dev_filename); + ret = 1; + } + } + + if (test_cachestat("tmpfilecachestat", true, true, + true, 4, O_CREAT | O_RDWR, 0400 | 0600)) + ksft_test_result_pass("cachestat works with a normal file\n"); + else { + ksft_test_result_fail("cachestat fails with normal file\n"); + ret = 1; + } + + if (test_cachestat_shmem()) + ksft_test_result_pass("cachestat works with a shmem file\n"); + else { + ksft_test_result_fail("cachestat fails with a shmem file\n"); + ret = 1; + } + + return ret; +}