glibc/sysdeps/unix/sysv/linux/include/sys/sysinfo.h

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linux/getsysstats.c: use sysinfo() instead of parsing /proc/meminfo Profiling git's test suite, Linus noted [1] that a disproportionately large amount of time was spent reading /proc/meminfo. This is done by the glibc functions get_phys_pages and get_avphys_pages, but they only need the MemTotal and MemFree fields, respectively. That same information can be obtained with a single syscall, sysinfo, instead of six: open, fstat, mmap, read, close, munmap. While sysinfo also provides more than necessary, it does a lot less work than what the kernel needs to do to provide the entire /proc/meminfo. Both strace -T and in-app microbenchmarks shows that the sysinfo() approach is roughly an order of magnitude faster. sysinfo() is much older than what glibc currently requires, so I don't think there's any reason to keep the old parsing code. Moreover, this makes get_[av]phys_pages work even in the absence of /proc. Linus noted that something as simple as 'bash -c "echo"' would trigger the reading of /proc/meminfo, but gdb says that many more applications than just bash are affected: Starting program: /bin/bash "-c" "echo" Breakpoint 1, __get_phys_pages () at ../sysdeps/unix/sysv/linux/getsysstats.c:283 283 ../sysdeps/unix/sysv/linux/getsysstats.c: No such file or directory. (gdb) bt So it seems that any application that uses qsort on a moderately sized array will incur this cost (once), which is obviously proportionately more expensive for lots of short-lived processes (such as the git test suite). [1] http://thread.gmane.org/gmane.linux.kernel/2019285 Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk> * sysdeps/unix/sysv/linux/getsysstats.c (__get_phys_pages): Use sysinfo system call instead of parsing /proc/meminfo. * sysdeps/unix/sysv/linux/getsysstats.c (__get_avphys_pages): Likewise.
2015-08-18 09:55:34 +00:00
/* Internal declarations for sys/sysinfo.h.
Copyright (C) 2015-2016 Free Software Foundation, Inc.
linux/getsysstats.c: use sysinfo() instead of parsing /proc/meminfo Profiling git's test suite, Linus noted [1] that a disproportionately large amount of time was spent reading /proc/meminfo. This is done by the glibc functions get_phys_pages and get_avphys_pages, but they only need the MemTotal and MemFree fields, respectively. That same information can be obtained with a single syscall, sysinfo, instead of six: open, fstat, mmap, read, close, munmap. While sysinfo also provides more than necessary, it does a lot less work than what the kernel needs to do to provide the entire /proc/meminfo. Both strace -T and in-app microbenchmarks shows that the sysinfo() approach is roughly an order of magnitude faster. sysinfo() is much older than what glibc currently requires, so I don't think there's any reason to keep the old parsing code. Moreover, this makes get_[av]phys_pages work even in the absence of /proc. Linus noted that something as simple as 'bash -c "echo"' would trigger the reading of /proc/meminfo, but gdb says that many more applications than just bash are affected: Starting program: /bin/bash "-c" "echo" Breakpoint 1, __get_phys_pages () at ../sysdeps/unix/sysv/linux/getsysstats.c:283 283 ../sysdeps/unix/sysv/linux/getsysstats.c: No such file or directory. (gdb) bt So it seems that any application that uses qsort on a moderately sized array will incur this cost (once), which is obviously proportionately more expensive for lots of short-lived processes (such as the git test suite). [1] http://thread.gmane.org/gmane.linux.kernel/2019285 Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk> * sysdeps/unix/sysv/linux/getsysstats.c (__get_phys_pages): Use sysinfo system call instead of parsing /proc/meminfo. * sysdeps/unix/sysv/linux/getsysstats.c (__get_avphys_pages): Likewise.
2015-08-18 09:55:34 +00:00
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _INCLUDE_SYS_SYSINFO_H
#define _INCLUDE_SYS_SYSINFO_H 1
#include_next <sys/sysinfo.h>
Installed header hygiene (BZ#20366): Test of installed headers. This adds a test to ensure that the problems fixed in the last several patches do not recur. Each directory checks the headers that it installs for two properties: first, each header must be compilable in isolation, as both C and C++, under a representative combination of language and library conformance levels; second, there is a blacklist of identifiers that may not appear in any installed header, currently consisting of the legacy BSD typedefs. (There is an exemption for the headers that define those typedefs, and for the RPC headers. It may be necessary to make this more sophisticated if we add more stuff to the blacklist in the future.) In order for this test to work correctly, every wrapper header that actually defines something must guard those definitions with #ifndef _ISOMAC. This is the existing mechanism used by the conform/ tests to tell wrapper headers not to define anything that the public header wouldn't, and not to use anything from libc-symbols.h. conform/ only cares for headers that we need to check for standards conformance, whereas this test applies to *every* header. (Headers in include/ that are either installed directly, or are internal-use-only and do *not* correspond to any installed header, are not affected.) * scripts/check-installed-headers.sh: New script. * Rules: In each directory that defines header files to be installed, run check-installed-headers.sh on them as a special test. * Makefile: Likewise for the headers installed at top level. * include/aliases.h, include/alloca.h, include/argz.h * include/arpa/nameser.h, include/arpa/nameser_compat.h * include/elf.h, include/envz.h, include/err.h * include/execinfo.h, include/fpu_control.h, include/getopt.h * include/gshadow.h, include/ifaddrs.h, include/libintl.h * include/link.h, include/malloc.h, include/mcheck.h * include/mntent.h, include/netinet/ether.h * include/nss.h, include/obstack.h, include/printf.h * include/pty.h, include/resolv.h, include/rpc/auth.h * include/rpc/auth_des.h, include/rpc/auth_unix.h * include/rpc/clnt.h, include/rpc/des_crypt.h * include/rpc/key_prot.h, include/rpc/netdb.h * include/rpc/pmap_clnt.h, include/rpc/pmap_prot.h * include/rpc/pmap_rmt.h, include/rpc/rpc.h * include/rpc/rpc_msg.h, include/rpc/svc.h * include/rpc/svc_auth.h, include/rpc/xdr.h * include/rpcsvc/nis_callback.h, include/rpcsvc/nislib.h * include/rpcsvc/yp.h, include/rpcsvc/ypclnt.h * include/rpcsvc/ypupd.h, include/shadow.h * include/stdio_ext.h, include/sys/epoll.h * include/sys/file.h, include/sys/gmon.h, include/sys/ioctl.h * include/sys/prctl.h, include/sys/profil.h * include/sys/statfs.h, include/sys/sysctl.h * include/sys/sysinfo.h, include/ttyent.h, include/utmp.h * sysdeps/arm/nacl/include/bits/setjmp.h * sysdeps/mips/include/sys/asm.h * sysdeps/unix/sysv/linux/include/sys/sysinfo.h * sysdeps/unix/sysv/linux/include/sys/timex.h * sysdeps/x86/fpu/include/bits/fenv.h: Add #ifndef _ISOMAC guard around internal declarations. Add multiple-inclusion guard if not already present.
2016-08-24 01:19:17 +00:00
# ifndef _ISOMAC
linux/getsysstats.c: use sysinfo() instead of parsing /proc/meminfo Profiling git's test suite, Linus noted [1] that a disproportionately large amount of time was spent reading /proc/meminfo. This is done by the glibc functions get_phys_pages and get_avphys_pages, but they only need the MemTotal and MemFree fields, respectively. That same information can be obtained with a single syscall, sysinfo, instead of six: open, fstat, mmap, read, close, munmap. While sysinfo also provides more than necessary, it does a lot less work than what the kernel needs to do to provide the entire /proc/meminfo. Both strace -T and in-app microbenchmarks shows that the sysinfo() approach is roughly an order of magnitude faster. sysinfo() is much older than what glibc currently requires, so I don't think there's any reason to keep the old parsing code. Moreover, this makes get_[av]phys_pages work even in the absence of /proc. Linus noted that something as simple as 'bash -c "echo"' would trigger the reading of /proc/meminfo, but gdb says that many more applications than just bash are affected: Starting program: /bin/bash "-c" "echo" Breakpoint 1, __get_phys_pages () at ../sysdeps/unix/sysv/linux/getsysstats.c:283 283 ../sysdeps/unix/sysv/linux/getsysstats.c: No such file or directory. (gdb) bt So it seems that any application that uses qsort on a moderately sized array will incur this cost (once), which is obviously proportionately more expensive for lots of short-lived processes (such as the git test suite). [1] http://thread.gmane.org/gmane.linux.kernel/2019285 Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk> * sysdeps/unix/sysv/linux/getsysstats.c (__get_phys_pages): Use sysinfo system call instead of parsing /proc/meminfo. * sysdeps/unix/sysv/linux/getsysstats.c (__get_avphys_pages): Likewise.
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extern __typeof (sysinfo) __sysinfo __THROW;
Installed header hygiene (BZ#20366): Test of installed headers. This adds a test to ensure that the problems fixed in the last several patches do not recur. Each directory checks the headers that it installs for two properties: first, each header must be compilable in isolation, as both C and C++, under a representative combination of language and library conformance levels; second, there is a blacklist of identifiers that may not appear in any installed header, currently consisting of the legacy BSD typedefs. (There is an exemption for the headers that define those typedefs, and for the RPC headers. It may be necessary to make this more sophisticated if we add more stuff to the blacklist in the future.) In order for this test to work correctly, every wrapper header that actually defines something must guard those definitions with #ifndef _ISOMAC. This is the existing mechanism used by the conform/ tests to tell wrapper headers not to define anything that the public header wouldn't, and not to use anything from libc-symbols.h. conform/ only cares for headers that we need to check for standards conformance, whereas this test applies to *every* header. (Headers in include/ that are either installed directly, or are internal-use-only and do *not* correspond to any installed header, are not affected.) * scripts/check-installed-headers.sh: New script. * Rules: In each directory that defines header files to be installed, run check-installed-headers.sh on them as a special test. * Makefile: Likewise for the headers installed at top level. * include/aliases.h, include/alloca.h, include/argz.h * include/arpa/nameser.h, include/arpa/nameser_compat.h * include/elf.h, include/envz.h, include/err.h * include/execinfo.h, include/fpu_control.h, include/getopt.h * include/gshadow.h, include/ifaddrs.h, include/libintl.h * include/link.h, include/malloc.h, include/mcheck.h * include/mntent.h, include/netinet/ether.h * include/nss.h, include/obstack.h, include/printf.h * include/pty.h, include/resolv.h, include/rpc/auth.h * include/rpc/auth_des.h, include/rpc/auth_unix.h * include/rpc/clnt.h, include/rpc/des_crypt.h * include/rpc/key_prot.h, include/rpc/netdb.h * include/rpc/pmap_clnt.h, include/rpc/pmap_prot.h * include/rpc/pmap_rmt.h, include/rpc/rpc.h * include/rpc/rpc_msg.h, include/rpc/svc.h * include/rpc/svc_auth.h, include/rpc/xdr.h * include/rpcsvc/nis_callback.h, include/rpcsvc/nislib.h * include/rpcsvc/yp.h, include/rpcsvc/ypclnt.h * include/rpcsvc/ypupd.h, include/shadow.h * include/stdio_ext.h, include/sys/epoll.h * include/sys/file.h, include/sys/gmon.h, include/sys/ioctl.h * include/sys/prctl.h, include/sys/profil.h * include/sys/statfs.h, include/sys/sysctl.h * include/sys/sysinfo.h, include/ttyent.h, include/utmp.h * sysdeps/arm/nacl/include/bits/setjmp.h * sysdeps/mips/include/sys/asm.h * sysdeps/unix/sysv/linux/include/sys/sysinfo.h * sysdeps/unix/sysv/linux/include/sys/timex.h * sysdeps/x86/fpu/include/bits/fenv.h: Add #ifndef _ISOMAC guard around internal declarations. Add multiple-inclusion guard if not already present.
2016-08-24 01:19:17 +00:00
# endif /* _ISOMAC */
linux/getsysstats.c: use sysinfo() instead of parsing /proc/meminfo Profiling git's test suite, Linus noted [1] that a disproportionately large amount of time was spent reading /proc/meminfo. This is done by the glibc functions get_phys_pages and get_avphys_pages, but they only need the MemTotal and MemFree fields, respectively. That same information can be obtained with a single syscall, sysinfo, instead of six: open, fstat, mmap, read, close, munmap. While sysinfo also provides more than necessary, it does a lot less work than what the kernel needs to do to provide the entire /proc/meminfo. Both strace -T and in-app microbenchmarks shows that the sysinfo() approach is roughly an order of magnitude faster. sysinfo() is much older than what glibc currently requires, so I don't think there's any reason to keep the old parsing code. Moreover, this makes get_[av]phys_pages work even in the absence of /proc. Linus noted that something as simple as 'bash -c "echo"' would trigger the reading of /proc/meminfo, but gdb says that many more applications than just bash are affected: Starting program: /bin/bash "-c" "echo" Breakpoint 1, __get_phys_pages () at ../sysdeps/unix/sysv/linux/getsysstats.c:283 283 ../sysdeps/unix/sysv/linux/getsysstats.c: No such file or directory. (gdb) bt So it seems that any application that uses qsort on a moderately sized array will incur this cost (once), which is obviously proportionately more expensive for lots of short-lived processes (such as the git test suite). [1] http://thread.gmane.org/gmane.linux.kernel/2019285 Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk> * sysdeps/unix/sysv/linux/getsysstats.c (__get_phys_pages): Use sysinfo system call instead of parsing /proc/meminfo. * sysdeps/unix/sysv/linux/getsysstats.c (__get_avphys_pages): Likewise.
2015-08-18 09:55:34 +00:00
#endif /* sys/sysinfo.h */