From 88537aac0b3840314d3a5cc401a7fc400c069bc9 Mon Sep 17 00:00:00 2001 From: Nhat Pham Date: Tue, 2 May 2023 18:36:08 -0700 Subject: [PATCH] selftests: add selftests for cachestat Test cachestat on a newly created file, /dev/ files, /proc/ files and a directory. Also test on a shmem file (which can also be tested with huge pages since tmpfs supports huge pages). [colin.i.king@gmail.com: fix spelling mistake "trucate" -> "truncate"] Link: https://lkml.kernel.org/r/20230505110855.2493457-1-colin.i.king@gmail.com [mpe@ellerman.id.au: avoid excessive stack allocation] Link: https://lkml.kernel.org/r/877ctfa6yv.fsf@mail.lhotse Link: https://lkml.kernel.org/r/20230503013608.2431726-4-nphamcs@gmail.com Signed-off-by: Nhat Pham Signed-off-by: Colin Ian King Signed-off-by: Michael Ellerman Acked-by: Johannes Weiner Cc: Brian Foster Cc: Matthew Wilcox (Oracle) Cc: Michael Kerrisk Cc: Colin Ian King Cc: Michael Ellerman Signed-off-by: Andrew Morton --- MAINTAINERS | 7 + tools/testing/selftests/Makefile | 1 + tools/testing/selftests/cachestat/.gitignore | 2 + tools/testing/selftests/cachestat/Makefile | 8 + tools/testing/selftests/cachestat/test_cachestat.c | 269 +++++++++++++++++++++ 5 files changed, 287 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 250518f..ce5f343 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -4486,6 +4486,13 @@ 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 90a62cf..5d6fc3f 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 0000000..d6c30b4 --- /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 0000000..fca73aa --- /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 0000000..54d09b8 --- /dev/null +++ b/tools/testing/selftests/cachestat/test_cachestat.c @@ -0,0 +1,269 @@ +// 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) +{ + int random_fd = open("/dev/urandom", O_RDONLY); + char *cursor, *data; + int remained; + bool ret; + + if (random_fd < 0) { + ksft_print_msg("Unable to access urandom.\n"); + ret = false; + goto out; + } + + data = malloc(filesize); + if (!data) { + ksft_print_msg("Unable to allocate data.\n"); + ret = false; + goto close_random_fd; + } + + remained = filesize; + 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 out_free_data; + } + + 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 out_free_data; + } + + remained -= write_len; + cursor += write_len; + } + + ret = true; +out_free_data: + free(data); +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; + struct cachestat_range cs_range = { 0, filesize }; + + int fd = open(filename, open_flags, open_mode); + + if (fd == -1) { + ksft_print_msg("Unable to create/open file.\n"); + ret = false; + 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, &cs_range, &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, &cs_range, &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; + size_t compute_len = PS * 512; + struct cachestat_range cs_range = { PS, compute_len }; + 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 truncate 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, &cs_range, &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; +} -- 2.7.4