Messages in this thread | | | From | Ian Rogers <> | Date | Wed, 6 Dec 2023 21:13:54 -0800 | Subject | Re: [PATCH v5 06/50] tools lib api: Add io_dir an allocation free readdir alternative |
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On Thu, Nov 30, 2023 at 1:25 PM Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > Em Thu, Nov 30, 2023 at 09:56:42AM -0800, Ian Rogers escreveu: > > On Thu, Nov 30, 2023 at 9:21 AM Arnaldo Carvalho de Melo > > <acme@kernel.org> wrote: > > > > > > Em Mon, Nov 27, 2023 at 02:08:18PM -0800, Ian Rogers escreveu: > > > > 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. > > > > > > Now, on some systems: > > > > > > CC /tmp/build/perf/pmu-events/pmu-events.o > > > In file included from util/machine.c:39: > > > /tmp/build/perf/libapi/include/api/io_dir.h: In function ‘io_dir__readdir’: > > > /tmp/build/perf/libapi/include/api/io_dir.h:46:16: error: implicit declaration of function ‘getdents64’; did you mean ‘getentropy’? [-Werror=implicit-function-declaration] > > > ssize_t rc = getdents64(iod->dirfd, iod->buff, sizeof(iod->buff)); > > > ^~~~~~~~~~ > > > getentropy > > > CC /tmp/build/perf/tests/workloads/brstack.o > > > CC /tmp/build/perf/tests/workloads/datasym.o > > > CC /tmp/build/perf/util/maps.o > > > > > > Sorry for that. Is it a _GNU_SOURCE issue? I thought we generally had > > Nope, some systems just don't have that function in its libc, for > instance, a Red Hat derivative with glibc 2.28: > > glibc-2.28-189.5.el8_6.x86_64 > > [perfbuilder@56645cef2169 /]$ grep -r getdents64 /usr/include > /usr/include/bits/syscall.h:#ifdef __NR_getdents64 > /usr/include/bits/syscall.h:# define SYS_getdents64 __NR_getdents64 > /usr/include/asm-generic/unistd.h:#define __NR_getdents64 61 > /usr/include/asm-generic/unistd.h:__SYSCALL(__NR_getdents64, sys_getdents64) > /usr/include/sanitizer/linux_syscall_hooks.h:#define __sanitizer_syscall_pre_getdents64(fd, dirent, count) \ > /usr/include/sanitizer/linux_syscall_hooks.h: __sanitizer_syscall_pre_impl_getdents64((long)(fd), (long)(dirent), \ > /usr/include/sanitizer/linux_syscall_hooks.h:#define __sanitizer_syscall_post_getdents64(res, fd, dirent, count) \ > /usr/include/sanitizer/linux_syscall_hooks.h: __sanitizer_syscall_post_impl_getdents64(res, (long)(fd), (long)(dirent), \ > /usr/include/sanitizer/linux_syscall_hooks.h:void __sanitizer_syscall_pre_impl_getdents64(long fd, long dirent, long count); > /usr/include/sanitizer/linux_syscall_hooks.h:void __sanitizer_syscall_post_impl_getdents64(long res, long fd, long dirent, > /usr/include/asm/unistd_64.h:#define __NR_getdents64 217 > /usr/include/asm/unistd_x32.h:#define __NR_getdents64 (__X32_SYSCALL_BIT + 217) > /usr/include/asm/unistd_32.h:#define __NR_getdents64 220 > [perfbuilder@56645cef2169 /]$ > > Systems with musl libc fail differently: > > 6 19.51 alpine:3.18 : FAIL gcc version 12.2.1 20220924 (Alpine 12.2.1_git20220924-r10) > CC /tmp/build/perf/util/sample-raw.o > CC /tmp/build/perf/tests/kmod-path.o > CC /tmp/build/perf/tests/thread-map.o > CC /tmp/build/perf/tests/topology.o > In file included from util/machine.c:39: > /tmp/build/perf/libapi/include/api/io_dir.h: In function 'io_dir__readdir': > /tmp/build/perf/libapi/include/api/io_dir.h:46:56: error: passing argument 2 of 'getdents' from incompatible pointer type [-Werror=incompatible-pointer-types] > 46 | ssize_t rc = getdents64(iod->dirfd, iod->buff, sizeof(iod->buff)); > | ~~~^~~~~~ > | | > | struct io_dirent64 * > In file included from util/machine.c:2: > /usr/include/dirent.h:52:19: note: expected 'struct dirent *' but argument is of type 'struct io_dirent64 *' > 52 | int getdents(int, struct dirent *, size_t); > | ^~~~~~~~~~~~~~~ > > Their devel distro also fails like that: > > 7 20.49 alpine:edge : FAIL gcc version 13.1.1 20230722 (Alpine 13.1.1_git20230722) > CC /tmp/build/perf/tests/sdt.o > CC /tmp/build/perf/util/maps.o > CC /tmp/build/perf/tests/is_printable_array.o > CC /tmp/build/perf/util/intel-pt-decoder/intel-pt-insn-decoder.o > In file included from util/machine.c:39: > /tmp/build/perf/libapi/include/api/io_dir.h: In function 'io_dir__readdir': > /tmp/build/perf/libapi/include/api/io_dir.h:46:56: error: passing argument 2 of 'getdents' from incompatible pointer type [-Werror=incompatible-pointer-types] > 46 | ssize_t rc = getdents64(iod->dirfd, iod->buff, sizeof(iod->buff)); > | ~~~^~~~~~ > | | > | struct io_dirent64 * > In file included from util/machine.c:2: > /usr/include/dirent.h:52:19: note: expected 'struct dirent *' but argument is of type 'struct io_dirent64 *' > 52 | int getdents(int, struct dirent *, size_t); > | ^~~~~~~~~~~~~~~ > CC /tmp/build/perf/tests/bitmap.o > > And then we have nolibc: > > ⬢[acme@toolbox perf-tools-next]$ find tools/ -name nolibc > tools/include/nolibc > tools/testing/selftests/nolibc > ⬢[acme@toolbox perf-tools-next]$ grep getdents64 tools/include/nolibc/* > tools/include/nolibc/sys.h: * int getdents64(int fd, struct linux_dirent64 *dirp, int count); > tools/include/nolibc/sys.h:int sys_getdents64(int fd, struct linux_dirent64 *dirp, int count) > tools/include/nolibc/sys.h: return my_syscall3(__NR_getdents64, fd, dirp, count); > tools/include/nolibc/sys.h:int getdents64(int fd, struct linux_dirent64 *dirp, int count) > tools/include/nolibc/sys.h: return __sysret(sys_getdents64(fd, dirp, count)); > tools/include/nolibc/types.h:/* for getdents64() */ > ⬢[acme@toolbox perf-tools-next]$ > > On musl libc systems: > > / $ grep -A1 -B20 getdents64 /usr/include/*.h > /usr/include/dirent.h-#define DT_SOCK 12 > /usr/include/dirent.h-#define DT_WHT 14 > /usr/include/dirent.h-#define IFTODT(x) ((x)>>12 & 017) > /usr/include/dirent.h-#define DTTOIF(x) ((x)<<12) > /usr/include/dirent.h-int getdents(int, struct dirent *, size_t); > /usr/include/dirent.h-#endif > /usr/include/dirent.h- > /usr/include/dirent.h-#ifdef _GNU_SOURCE > /usr/include/dirent.h-int versionsort(const struct dirent **, const struct dirent **); > /usr/include/dirent.h-#endif > /usr/include/dirent.h- > /usr/include/dirent.h-#if defined(_LARGEFILE64_SOURCE) || defined(_GNU_SOURCE) > /usr/include/dirent.h-#define dirent64 dirent > /usr/include/dirent.h-#define readdir64 readdir > /usr/include/dirent.h-#define readdir64_r readdir_r > /usr/include/dirent.h-#define scandir64 scandir > /usr/include/dirent.h-#define alphasort64 alphasort > /usr/include/dirent.h-#define versionsort64 versionsort > /usr/include/dirent.h-#define off64_t off_t > /usr/include/dirent.h-#define ino64_t ino_t > /usr/include/dirent.h:#define getdents64 getdents > /usr/include/dirent.h-#endif > / $
I'm confused. It seems nolibc has support, musl doesn't and with old glibcs it depends. I added a feature test in a the latest patch series to hopefully workaround this: https://lore.kernel.org/lkml/20231207050433.1426834-1-irogers@google.com/ Could you help check and I suspect the syscall implementation needs some work for if SYS_getdents64 isn't defined, etc.
Thanks, Ian
> > _GNU_SOURCE defined on the command line for reallocarray. Maybe we > > shouldn't define this on the command line and do it immediately before > > the relevant include with: > > > > #ifndef _GNU_SOURCE > > #define _GNU_SOURCE > > #endif > > > > like in tools/perf/util/intel-pt-decoder/intel-pt-decoder.c > > > > Thanks, > > Ian > > > > > > > > > Signed-off-by: Ian Rogers <irogers@google.com> > > > > --- > > > > tools/lib/api/Makefile | 2 +- > > > > tools/lib/api/io_dir.h | 75 ++++++++++++++++++++++++++++++++++++++++++ > > > > 2 files changed, 76 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..f3479006edb6 > > > > --- /dev/null > > > > +++ b/tools/lib/api/io_dir.h > > > > @@ -0,0 +1,75 @@ > > > > +/* 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, 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 > > > > -- > > > > 2.43.0.rc1.413.gea7ed67945-goog > > > > > > > > > > -- > > > > > > - Arnaldo > > -- > > - Arnaldo
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