GetTickCount in Linux

In Linux, GetTickCount -- general Linux technology-Linux programming and kernel information. The following is a detailed description. In Windows, GetTickCount is very easy to use. In Linux, I did not find an alternative function at first (a little dish). At that time, a module in the project used this function, I had to use gettimeofday to indirectly meet the requirements, but this is not the real time for running after the system starts.

A few days ago, the Review code thought it was necessary to study it again.

CODE: SYSINFO (2) Linux Programmer's Manual SYSINFO (2) NAME Sysinfo-returns information on overall system statistics SYNOPSIS # Include Int sysinfo (struct sysinfo * info ); DESCRIPTION Until Linux 2.3.16, sysinfo () used to return information in The following structure: Struct sysinfo { Long uptime;/* Seconds since boot */ Unsigned long loads [3];/* 1, 5, and 15 minute load averages */ Unsigned long totalram;/* Total usable main memory size */ Unsigned long freeram;/* Available memory size */ Unsigned long sharedram;/* Amount of shared memory */ Unsigned long bufferram;/* Memory used by buffers */ Unsigned long totalswap;/* Total swap space size */ Unsigned long freeswap;/* swap space still available */ Unsigned short procs;/* Number of current processes */ Char _ f [22];/* Pads structure to 64 bytes */ }; And the sizes were given in bytes. Since Linux 2.3.23 (i386), 2.3.48 (all ubuntures) Structure is: Struct sysinfo { Long uptime;/* Seconds since boot */ Unsigned long loads [3];/* 1, 5, and 15 minute load averages */ Unsigned long totalram;/* Total usable main memory size */ Unsigned long freeram;/* Available memory size */ Unsigned long sharedram;/* Amount of shared memory */ Unsigned long bufferram;/* Memory used by buffers */ Unsigned long totalswap;/* Total swap space size */ Unsigned long freeswap;/* swap space still available */ Unsigned short procs;/* Number of current processes */ Unsigned long totalhigh;/* Total high memory size */ Unsigned long freehigh;/* Available high memory size */ Unsigned int mem_unit;/* Memory unit size in bytes */ Char _ f [20-2 * sizeof (long)-sizeof (int)];/* Padding for libc5 */ }; And the sizes are given as multiples of mem_unit bytes. Sysinfo () provides a simple way of getting overall system Statistics. This is more portable than reading/dev/kmem. For an example of its use, see intro (2 ). RETURN VALUE On success, zero is returned. On error,-1 is returned, and Errno is set appropriately. ERRORS EFAULT pointer to struct sysinfo is invalid CONFORMING This function is Linux specific, and shoshould not be used in Programs intended to be portable. The Linux kernel has a sysinfo () system call since 0.98.pl6. Linux libc contains a sysinfo () routine since 5.3.5, and glibc The has one since 1.90. SEE ALSO Proc (5)