From d118b08f7eee6d6f44b4c549cf22d6b078e2ed73 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Fri, 21 Feb 2025 22:10:06 -0800 Subject: [PATCH] tools lib api: Add io_dir an allocation free readdir alternative glibc's opendir allocates a minimum of 32kb, when called recursively for a directory tree the memory consumption can add up - nearly 300kb during perf start-up when processing modules. Add a stack allocated variant of readdir sized a little more than 1kb. As getdents64 may be missing from libc, add support using syscall. As the system call number maybe missing, add #defines for those. Note, an earlier version of this patch had a feature test for getdents64 but there were problems on certains distros where getdents64 would be #define renamed to getdents breaking the code. The syscall use was made uncondtional to work around this. There is context in: https://lore.kernel.org/lkml/20231207050433.1426834-1-irogers@google.com/ Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250222061015.303622-2-irogers@google.com Signed-off-by: Namhyung Kim --- tools/lib/api/Makefile | 2 +- tools/lib/api/io_dir.h | 104 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 105 insertions(+), 1 deletion(-) create mode 100644 tools/lib/api/io_dir.h diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile index 7f6396087b46..8665c799e0fa 100644 --- a/tools/lib/api/Makefile +++ b/tools/lib/api/Makefile @@ -95,7 +95,7 @@ install_lib: $(LIBFILE) $(call do_install_mkdir,$(libdir_SQ)); \ cp -fpR $(LIBFILE) $(DESTDIR)$(libdir_SQ) -HDRS := cpu.h debug.h io.h +HDRS := cpu.h debug.h io.h io_dir.h FD_HDRS := fd/array.h FS_HDRS := fs/fs.h fs/tracing_path.h INSTALL_HDRS_PFX := $(DESTDIR)$(prefix)/include/api diff --git a/tools/lib/api/io_dir.h b/tools/lib/api/io_dir.h new file mode 100644 index 000000000000..aab73393d2a2 --- /dev/null +++ b/tools/lib/api/io_dir.h @@ -0,0 +1,104 @@ +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ +/* + * Lightweight directory reading library. + */ +#ifndef __API_IO_DIR__ +#define __API_IO_DIR__ + +#include +#include +#include +#include +#include +#include + +#if !defined(SYS_getdents64) +#if defined(__x86_64__) || defined(__arm__) + #define SYS_getdents64 217 +#elif defined(__i386__) || defined(__s390x__) || defined(__sh__) + #define SYS_getdents64 220 +#elif defined(__alpha__) + #define SYS_getdents64 377 +#elif defined(__mips__) + #define SYS_getdents64 308 +#elif defined(__powerpc64__) || defined(__powerpc__) + #define SYS_getdents64 202 +#elif defined(__sparc64__) || defined(__sparc__) + #define SYS_getdents64 154 +#elif defined(__xtensa__) + #define SYS_getdents64 60 +#else + #define SYS_getdents64 61 +#endif +#endif /* !defined(SYS_getdents64) */ + +static inline ssize_t perf_getdents64(int fd, void *dirp, size_t count) +{ +#ifdef MEMORY_SANITIZER + memset(dirp, 0, count); +#endif + return syscall(SYS_getdents64, fd, dirp, count); +} + +struct io_dirent64 { + ino64_t d_ino; /* 64-bit inode number */ + off64_t d_off; /* 64-bit offset to next structure */ + unsigned short d_reclen; /* Size of this dirent */ + unsigned char d_type; /* File type */ + char d_name[NAME_MAX + 1]; /* Filename (null-terminated) */ +}; + +struct io_dir { + int dirfd; + ssize_t available_bytes; + struct io_dirent64 *next; + struct io_dirent64 buff[4]; +}; + +static inline void io_dir__init(struct io_dir *iod, int dirfd) +{ + iod->dirfd = dirfd; + iod->available_bytes = 0; +} + +static inline void io_dir__rewinddir(struct io_dir *iod) +{ + lseek(iod->dirfd, 0, SEEK_SET); + iod->available_bytes = 0; +} + +static inline struct io_dirent64 *io_dir__readdir(struct io_dir *iod) +{ + struct io_dirent64 *entry; + + if (iod->available_bytes <= 0) { + ssize_t rc = perf_getdents64(iod->dirfd, iod->buff, sizeof(iod->buff)); + + if (rc <= 0) + return NULL; + iod->available_bytes = rc; + iod->next = iod->buff; + } + entry = iod->next; + iod->next = (struct io_dirent64 *)((char *)entry + entry->d_reclen); + iod->available_bytes -= entry->d_reclen; + return entry; +} + +static inline bool io_dir__is_dir(const struct io_dir *iod, struct io_dirent64 *dent) +{ + if (dent->d_type == DT_UNKNOWN) { + struct stat st; + + if (fstatat(iod->dirfd, dent->d_name, &st, /*flags=*/0)) + return false; + + if (S_ISDIR(st.st_mode)) { + dent->d_type = DT_DIR; + return true; + } + } + return dent->d_type == DT_DIR; +} + +#endif /* __API_IO_DIR__ */ -- 2.50.1