Coda File System

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13. The Fast Time Package

The Fast Time package allows the caller to find out the current time of day without incurring the expense of a kernel call. It works by mapping the page of the kernel that has the kernels time-of-day variable and examining it directly. Currently, this package only works on Suns. You may call the routines on other machines, but they will run more slowly.

The initialization routine for this package is fairly expensive since it does a lookup of a kernel symbol via nlist (). If you have a program which runs for only a short time, you may wish to call @FT(Init) with the notReally parameter true to prevent the lookup from taking place. This is useful if you are using another package that uses Fast Time (such as RPC2).

13.1 Fast Time Primitives

FT_Init -- Initialize the Fast Time package

Call:

int FT_Init( in int printErrors > , @w < in int notReally )

Parameters:

printErrors

Print error messages on stderr if somethingn goes wrong

notReally

Dont really do the memory mapping. Make FT_GetTimeOfDay

Completion Codes:

0

No problems

-1

Error in initialization

Description:

This call mmaps the kernel page with the time of day variable. If the routine returns -1, calls to FT_GetTimeOfDay will still work properly, but will make a kernel call. )

FTGetTimeOfDay -- Get the time of day from the mapped kernel pages

Call:

int FTGetTimeOfDay( )

Parameters:

tv

Where to put the time of day

tz

Where to put the time zone information

Completion Codes:

0

No problem

-1

Something went wrong

Description:

This function has the same calling sequence as the kernels gettimeofday routine. If the tz parameter is not zero, or if initialization failed, or if the notReally parameter in the initialization was true, then this routine calls gettimeofday . Otherwise, it looks in the mapped page of the kernel to get the time of day. >

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