From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0FA2E1A841F; Wed, 19 Feb 2025 21:51:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740001881; cv=none; b=kxHt75qmIZcT7u20lT3hxlrhKk5JZbomuapXmGv8fs5l2k51YtMyABG1Pp+bEjLZHGi0HWqHH32+xo+UhsFe4/rUMRQdW5rBjhOp96PIn5xr0TYtPdl/sM9QsT52P7l0wzJ6J81vK91jfX019onmL6dDfkrQsH0BtRgRV/jYeWA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740001881; c=relaxed/simple; bh=H3b6RBRBHUE0izguuOJatBXxCTwXSbSbQM2q3tYgp34=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=e/49aJS7vtRVHMGAtNmNFqbpCfvL7RA7qtp8vIleSdAMVtfPZUB15ZaI+gDw3p5eFu6KX4275hGdWxm6C+oHd+UnY62ukuM/XI6woNnTmZCB62i3++slsc1BqJ4DNaeLPJOPGgOX3sG8t+uxQLOGcHcIWOfQo+CmgxdUpI8KoH4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eV7UxlGV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eV7UxlGV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC239C4CED1; Wed, 19 Feb 2025 21:51:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740001880; bh=H3b6RBRBHUE0izguuOJatBXxCTwXSbSbQM2q3tYgp34=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eV7UxlGVj0ncqLp/JM9yFF0uHiUZEUrNtTyVWGZlwPa5pZbrLs5NZmvmv+69qVOBH Z0ai6brrQGeikxwsGJx02TscoGPySEGfrW/gnZFkYClVL1oLXW6+lfOJ/cA1koxNsA Sn9nNjiKis6UV354PE6g29Ibl8c5jF4FZbBI+OYozNwUnG0HGCT+UAhZWcDyFKv4nY S9xoxMdXg5P175kPji/2YI1catpKp32BvyeMGMC9faWXtjDGVLB1GMvQvTNQtUsW2K YMVjytx5Mh5qGiCdigC8hk9a8R1Bzdcw7QOfGoE3FMYFx17gbCQb+8jqdCiy6ARauO rBmNV/hB2kVbw== Date: Wed, 19 Feb 2025 13:51:18 -0800 From: Namhyung Kim To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , Sam James , Jesper Juhl , James Clark , Zhongqiu Han , Yicong Yang , Thomas Richter , Michael Petlan , Veronika Molnarova , Anne Macedo , Dominique Martinet , Jean-Philippe Romain , Junhao He , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Krzysztof =?utf-8?Q?=C5=81opatowski?= Subject: Re: [PATCH v2 1/7] tools lib api: Add io_dir an allocation free readdir alternative Message-ID: References: <20250207232452.994822-1-irogers@google.com> <20250207232452.994822-2-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250207232452.994822-2-irogers@google.com> On Fri, Feb 07, 2025 at 03:24:42PM -0800, Ian Rogers 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. > > As getdents64 may be missing from libc, add support using syscall. > 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 > --- > tools/lib/api/Makefile | 2 +- > tools/lib/api/io_dir.h | 93 ++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 94 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..c84738923c96 > --- /dev/null > +++ b/tools/lib/api/io_dir.h > @@ -0,0 +1,93 @@ > +/* 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__) > +#define SYS_getdents64 217 > +#elif defined(__aarch64__) > +#define SYS_getdents64 61 > +#endif > +#endif > + > +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); Unfortunately this fails to build on my i386 vm (and probably other old archs don't have SYS_getdents64 yet). In file included from util/pmus.c:6: /build/libapi/include/api/io_dir.h: In function 'perf_getdents64': /build/libapi/include/api/io_dir.h:28:24: error: 'SYS_getdents64' undeclared (first use in this function); did you mean 'perf_getdents64'? 28 | return syscall(SYS_getdents64, fd, dirp, count); | ^~~~~~~~~~~~~~ | perf_getdents64 > +} > +#endif Maybe mismatched. Thanks, Namhyung > + > +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 > -- > 2.48.1.502.g6dc24dfdaf-goog >