diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/getsysstats.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/getsysstats.c | 88 |
1 files changed, 30 insertions, 58 deletions
diff --git a/sysdeps/unix/sysv/linux/getsysstats.c b/sysdeps/unix/sysv/linux/getsysstats.c index 410f1a975f..5bb5543840 100644 --- a/sysdeps/unix/sysv/linux/getsysstats.c +++ b/sysdeps/unix/sysv/linux/getsysstats.c @@ -278,81 +278,53 @@ __get_nprocs_conf (void) } weak_alias (__get_nprocs_conf, get_nprocs_conf) -/* General function to get information about memory status from proc - filesystem. */ + +/* Compute (num*mem_unit)/pagesize, but avoid overflowing long int. + In practice, mem_unit is never bigger than the page size, so after + the first loop it is 1. [In the kernel, it is initialized to + PAGE_SIZE in mm/page_alloc.c:si_meminfo(), and then in + kernel.sys.c:do_sysinfo() it is set to 1 if unsigned long can + represent all the sizes measured in bytes]. */ static long int -internal_function -phys_pages_info (const char *format) +sysinfo_mempages (unsigned long int num, unsigned int mem_unit) { - char buffer[8192]; - long int result = -1; + unsigned long int ps = __getpagesize (); - /* If we haven't found an appropriate entry return 1. */ - FILE *fp = fopen ("/proc/meminfo", "rce"); - if (fp != NULL) + while (mem_unit > 1 && ps > 1) { - /* No threads use this stream. */ - __fsetlocking (fp, FSETLOCKING_BYCALLER); - - result = 0; - /* Read all lines and count the lines starting with the - string "processor". We don't have to fear extremely long - lines since the kernel will not generate them. 8192 - bytes are really enough. */ - while (__fgets_unlocked (buffer, sizeof buffer, fp) != NULL) - if (sscanf (buffer, format, &result) == 1) - { - result /= (__getpagesize () / 1024); - break; - } - - fclose (fp); + mem_unit >>= 1; + ps >>= 1; } - - if (result == -1) - /* We cannot get the needed value: signal an error. */ - __set_errno (ENOSYS); - - return result; + num *= mem_unit; + while (ps > 1) + { + ps >>= 1; + num >>= 1; + } + return num; } - -/* Return the number of pages of physical memory in the system. There - is currently (as of version 2.0.21) no system call to determine the - number. It is planned for the 2.1.x series to add this, though. - - One possibility to implement it for systems using Linux 2.0 is to - examine the pseudo file /proc/cpuinfo. Here we have one entry for - each processor. - - But not all systems have support for the /proc filesystem. If it - is not available we return -1 as an error signal. */ +/* Return the number of pages of total/available physical memory in + the system. This used to be done by parsing /proc/meminfo, but + that's unnecessarily expensive (and /proc is not always available). + The sysinfo syscall provides the same information, and has been + available at least since kernel 2.3.48. */ long int __get_phys_pages (void) { - /* XXX Here will come a test for the new system call. */ + struct sysinfo info; - return phys_pages_info ("MemTotal: %ld kB"); + __sysinfo (&info); + return sysinfo_mempages (info.totalram, info.mem_unit); } weak_alias (__get_phys_pages, get_phys_pages) - -/* Return the number of available pages of physical memory in the - system. There is currently (as of version 2.0.21) no system call - to determine the number. It is planned for the 2.1.x series to add - this, though. - - One possibility to implement it for systems using Linux 2.0 is to - examine the pseudo file /proc/cpuinfo. Here we have one entry for - each processor. - - But not all systems have support for the /proc filesystem. If it - is not available we return -1 as an error signal. */ long int __get_avphys_pages (void) { - /* XXX Here will come a test for the new system call. */ + struct sysinfo info; - return phys_pages_info ("MemFree: %ld kB"); + __sysinfo (&info); + return sysinfo_mempages (info.freeram, info.mem_unit); } weak_alias (__get_avphys_pages, get_avphys_pages) |