Date: Tue, 04 Mar 2003 15:41:13 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: jan@digitaldaemon.com Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: 'ticks' in kernel. Message-ID: <20030304.154113.90196009.imp@bsdimp.com> In-Reply-To: <3E64F7B2.9040008@digitaldaemon.com> References: <3E64E941.3030205@digitaldaemon.com> <20030304.104403.34570707.imp@bsdimp.com> <3E64F7B2.9040008@digitaldaemon.com>
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In message: <3E64F7B2.9040008@digitaldaemon.com>
Jan Knepper <jan@digitaldaemon.com> writes:
: How would they return me the 'value' of 'ticks'?
:
: The problem is... I have a value's somewhere that has been assigned from
: 'ticks', like:
: ptr -> value = ticks;
:
: at an other moment I need to do something like...
:
: age = boottime + ( ticks - ptr -> value ) / factor;
:
: The problem in the second case however is that I can not seem to get to
: 'ticks' as it is userland code...
ptr->value should be set with getmicrotime() or microtime(). You can
then do a gettimeofday in userland to figure out the age.
MICROTIME(9) FreeBSD Kernel Developer's Manual MICROTIME(9)
NAME
microtime, getmicrotime, nanotime, getnanotime - get the current time
SYNOPSIS
#include <sys/time.h>
void
microtime(struct timeval *tv);
void
getmicrotime(struct timeval *tv);
void
nanotime(struct timespec *ts);
void
getnanotime(struct timespec *tsp);
DESCRIPTION
The microtime() and getmicrotime() functions store the system time as a
struct timeval at the address specified by tv. The nanotime() and
getnanotime() functions perform the same utility, but record the time as
a struct timespec instead.
Microtime() and nanotime() always query the timecounter to return the
current time as precisely as possible. Whereas getmicrotime() and
getnanotime() functions are abstractions which return a less precise, but
faster to obtain, time.
The intent of the getmicrotime() and getnanotime() functions is to
enforce the user's preference for timer accuracy versus execution time.
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