Messages in this thread | | | From | Namhyung Kim <> | Date | Wed, 25 Oct 2023 11:43:21 -0700 | Subject | Re: [PATCH v3 18/50] tools lib api: Add io_dir an allocation free readdir alternative |
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On Tue, Oct 24, 2023 at 3:24 PM Ian Rogers <irogers@google.com> wrote: > > 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);
Any chance of unaligned access?
> + 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);
You may want to save the type if it's a DIR.
Thanks, Namhyung
> + } > + return dent->d_type == DT_DIR; > +} > + > +#endif > -- > 2.42.0.758.gaed0368e0e-goog >
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