This patch consolidates all the non cancellable read calls to use
the __read_nocancel identifier. For non cancellable targets it will
be just a macro to call the default respective symbol while on Linux
will be a internal one.
Also, since it is used on libcrypto it is also exported in GLIBC_PRIVATE
namespace.
Checked on x86_64-linux-gnu, x86_64-linux-gnu-x32, and i686-linux-gnu.
* sysdeps/generic/not-cancel.h (read_not_cancel): Remove macro.
(__read_nocancel): New macro.
* sysdeps/unix/sysv/linux/Versions (libc) [GLIBC_PRIVATE]: Add
__read_nocancel.
* sysdeps/unix/sysv/linux/not-cancel.h (__read_nocancel): Remove
macro.
(__read_nocancel): New prototype.
* sysdeps/unix/sysv/linux/read.c (__read_nocancel): New function.
* catgets/open_catalog.c (__open_catalog): Replace read_not_cancel
with __read_nocancel.
* intl/loadmsgcat.c (read): Likewise.
* libio/fileops.c (_IO_file_read): Likewise.
* locale/loadlocale.c (_nl_load_locale): Likewise.
* login/utmp_file.c (getutent_r_file): Likewise.
(internal_getut_r): Likewise.
(getutline_r_file): Likewise.
* sysdeps/unix/sysv/linux/fips-private.h (fips_enable_p): Likewise.
* sysdeps/unix/sysv/linux/gethostid.c (gethostid): Likewise.
* sysdeps/unix/sysv/linux/getloadavg.c (getloadavg): Likewise.
* sysdeps/unix/sysv/linux/getlogin_r.c (__getlogin_r_loginuid):
Likewise.
* sysdeps/unix/sysv/linux/getsysstats.c (next_line): Likewise.
* sysdeps/unix/sysv/linux/i386/smp.h (is_smp_system): Likewise.
* sysdeps/unix/sysv/linux/ia64/has_cpuclock.c (has_cpuclock):
Likewise.
* sysdeps/unix/sysv/linux/libc_fatal.c (backtrace_and_maps):
Likewise.
* sysdeps/unix/sysv/linux/malloc-sysdep.h (check_may_shrink_heap):
Likewise.
* sysdeps/unix/sysv/linux/pthread_getname.c (pthread_getname_np):
Likewise.
* sysdeps/unix/sysv/linux/sysconf.c (__sysconf): Likewise.
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.
__get_nprocs is called from malloc code, but calls fgets_unlocked,
which is not an ISO C or POSIX function. This patch fixes it to call
a new __fgets_unlocked name instead.
Note: there are various other uses of fgets_unlocked in glibc's
libraries, and I haven't yet investigated which others might also be
problematic (called directly or indirectly from standard functions)
and so need to change to use __fgets_unlocked.
Tested for x86_64 (testsuite, and that disassembly of installed shared
libraries is unchanged by the patch).
[BZ #17582]
* libio/iofgets.c [weak_alias && !_IO_MTSAFE_IO]
(__fgets_unlocked): Add alias of _IO_fgets. Use libc_hidden_def.
* libio/iofgets_u.c (fgets_unlocked): Rename to __fgets_unlocked
and define as weak alias of __fgets_unlocked. Use
libc_hidden_weak.
(__fgets_unlocked): Use libc_hidden_def.
* include/stdio.h (__fgets_unlocked): Declare. Use
libc_hidden_proto.
* sysdeps/unix/sysv/linux/getsysstats.c (phys_pages_info): Use
__fgets_unlocked instead of fgets_unlocked.
* sysdeps/unix/sysv/linux/alpha/getsysstats.c
(GET_NPROCS_CONF_PARSER): Likewise.
* sysdeps/unix/sysv/linux/sparc/getsysstats.c
(GET_NPROCS_CONF_PARSER): Likewise.
This patch removes conditionals on __ASSUME_O_CLOEXEC, and on
O_CLOEXEC being defined, in sysdeps/unix/sysv/linux/, now that
O_CLOEXEC support can be unconditionally assumed.
The patch is conservative in what it changes and further followup
cleanups may be possible. It may be possible to remove dl-opendir.c,
but the patch does not do so, just removing a redundant undefine and
redefine of __ASSUME_O_CLOEXEC. Also, __ASSUME_O_CLOEXEC is defined
unconditionally for Hurd as well as Linux. Thus, if we decide that
O_CLOEXEC support is a required feature of any glibc port, we could
remove __ASSUME_O_CLOEXEC and all conditionals on it throughout glibc,
rather than just cleaning up sysdeps/unix/sysv/linux/.
Tested x86_64 that the disassembly of installed shared libraries is
unchanged by this patch.
* sysdeps/unix/sysv/linux/dl-opendir.c (__ASSUME_O_CLOEXEC): Do
not undefine and redefine.
* sysdeps/unix/sysv/linux/getsysstats.c (__get_nprocs)
[O_CLOEXEC]: Make code unconditional.
(__get_nprocs) [!O_CLOEXEC]: Remove conditional code.
* sysdeps/unix/sysv/linux/shm_open.c: Do not include
<kernel-features.h>.
[O_CLOEXEC && !__ASSUME_O_CLOEXEC] (have_o_cloexec): Remove
conditional variable definition.
(shm_open) [O_CLOEXEC]: Make code unconditional.
(shm_open) [!O_CLOEXEC || !__ASSUME_O_CLOEXEC]: Remove conditional
code.
The implementation of __get_nprocs uses a stactic variable to cache
the value of the current number of processors. The caching breaks when
'time (NULL) == 0':
$ cat nproc.c
#include <stdio.h>
#include <time.h>
#include <sys/time.h>
int main(int argc, char *argv[])
{
time_t t;
struct timeval tv = {0, 0};
printf("settimeofday({0, 0}, NULL) = %d\n", settimeofday(&tv, NULL));
t = time(NULL);
printf("Time: %d, CPUs: %d\n", (unsigned int)t, get_nprocs());
return 0;
}
$ gcc -O3 nproc.c
$ ./a.out
settimeofday({0, 0}, NULL) = -1
Time: 1401311578, CPUs: 4
$ sudo ./a.out
settimeofday({0, 0}, NULL) = 0
Time: 0, CPUs: 0
The problem is with the condition used to check whether a cached
value should be returned or not:
static int cached_result;
static time_t timestamp;
time_t now = time (NULL);
time_t prev = timestamp;
atomic_read_barrier ();
if (now == prev)
return cached_result;
This patch fixes the problem by ensuring that 'cached_result' has
been set at least once before returning it.
are always at least 4 bytes in the returned line.
2009-04-15 Jakub Jelinek <jakub@redhat.com>
* sysdeps/unix/sysv/linux/getsysstats.c (__get_nprocs): Check
__libc_use_alloca (8192), if the stack is too small use 512 bytes
instead of 8K. Stop searching in /proc/stat after hitting first
line not starting with cpu.
(next_line): Truncate too long
lines at buffer size * 3/4 instead of pretending there were line
breaks inside of large lines.
(GET_NPROCS_PARSER): Change parameters and use next_line.
(__get_nprocs): Rewrite to not use stdio routines.
* sysdeps/unix/sysv/linux/sparc/getsysstats.c (GET_NPROCS_PARSER):
Change parameters and use next_line.
* sysdeps/ieee754/dbl-64/e_pow.c (log1): Define and initialize
two52 locally.
(log2): Likewise.
* sysdeps/ieee754/dbl-64/upow.h: Remove definition of two52.
Patch by Simon Gee <simong@agile.tv>.
* sysdeps/unix/sysv/linux/getsysstats.c (__get_nprocs_conf):
Prefer reading /proc/stat since it is more uniform across
architectures.1
* manual/texinfo.tex: Update to latest official version.
2001-07-06 Paul Eggert <eggert@twinsun.com>
* manual/argp.texi: Remove ignored LGPL copyright notice; it's
not appropriate for documentation anyway.
* manual/libc-texinfo.sh: "Library General Public License" ->
"Lesser General Public License".
2001-07-06 Andreas Jaeger <aj@suse.de>
* All files under GPL/LGPL version 2: Place under LGPL version
2.1.
* sysdeps/generic/getsysstat.c: Change return value of get_phys_pages
and get_avphys_page to long int.
* sysdeps/unix/sysv/linux/getsysstat.c: Likewise.
* include/sys/sysinfo.h: Likewise.
* sysdeps/generic/sys/sysinfo.h: Likewise.
* sysdeps/unix/sysv/linux/sys/sysinfo.h: Likewise.
* sysdeps/unix/sysv/linux/getsysstats.c (get_proc_path): Cache
result. Search first in /etc/mtab (proc/mounts would be stupid).
If mount not in the file fall back on /proc.
1999-07-30 Andreas Schwab <schwab@suse.de>
* sysdeps/unix/sysv/linux/getsysstats.c (GET_NPROCS_PARSER): New
definition.
(__get_nprocs): Use it.
(__get_nprocs_conf): Define as separate function if
GET_NPROCS_CONF_PARSER is defined.
* sysdeps/unix/sysv/linux/alpha/getsysstats.c: New file.
* include/sys/sysinfo.h: New file.
* sysdeps/generic/sys/sysinfo.h: Remove declaration of internal
interface.
* sysdeps/unix/sysv/linux/sys/sysinfo.h: Likewise.
1999-07-30 H.J. Lu <hjl@gnu.org>
* libio/iofflush.c (fflush_unlocked): Weak aliase if
_IO_MTSAFE_IO is not defined.
* libio/clearerr.c (clearerr_unlocked): Likewise.
* libio/feof.c (feof_unlocked): Likewise.
* libio/ferror.c (ferror_unlocked): Likewise.
* libio/fputc.c (fputc_unlocked): Likewise.
* libio/getc.c (getc_unlocked, fgetc_unlocked): Likewise.
* libio/getchar.c (getchar_unlocked): Likewise.
* libio/putc.c (putc_unlocked): Likewise.
* libio/putchar.c (putchar_unlocked): Likewise.
1999-07-30 Thorsten Kukuk <kukuk@suse.de>
* sunrpc/Versions: Add svc_getreq_common, svc_getreq_poll,
svc_max_pollfd and svc_pollfd to GLIBC_2.2
* sunrpc/rpc/svc.h: Use rpc*_t types, add new prototypes
for svc_run/poll interface.
* sunrpc/rpc/types.h: Add rpc*_t typedefs.
* sunrpc/rpc_common.c: Add svc_pollfd and svc_max_pollfd as
global variable.
* sunrpc/svc.c: Add svc_getreq_poll and svc_getreq_common,
rewrite other svc_getreq* functions to use svc_getreq_common.
* sunrpc/svc_run.c: Use poll().
1999-07-30 Andreas Schwab <schwab@suse.de>
* Makerules: Put sysd-versions and Versions.all on
postclean-generated instead of common-generated.
1999-07-29 Andreas Jaeger <aj@arthur.rhein-neckar.de>
* manual/time.texi (Basic CPU Time): Note that clock_t can wrap
around and CLOCKS_PER_SEC is 1e6.
