Messages in this thread Patch in this message | | | Date | Tue, 24 Oct 2023 15:23:21 -0700 | Subject | [PATCH v3 18/50] tools lib api: Add io_dir an allocation free readdir alternative | From | Ian Rogers <> |
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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.
Signed-off-by: Ian Rogers <irogers@google.com> --- tools/lib/api/Makefile | 2 +- tools/lib/api/io_dir.h | 72 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 73 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 044860ac1ed1..186aa407de8c 100644 --- a/tools/lib/api/Makefile +++ b/tools/lib/api/Makefile @@ -99,7 +99,7 @@ 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..8a70c0718df5 --- /dev/null +++ b/tools/lib/api/io_dir.h @@ -0,0 +1,72 @@ +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ +/* + * Lightweight directory reading library. + */ +#ifndef __API_IO_DIR__ +#define __API_IO_DIR__ + +#include <dirent.h> +#include <fcntl.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/stat.h> + +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 = 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, const 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; + + return S_ISDIR(st.st_mode); + } + return dent->d_type == DT_DIR; +} + +#endif -- 2.42.0.758.gaed0368e0e-goog
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