How to avoid calling time(2)

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3 total messages Started by Bernard Fouche Wed, 27 Jan 1993 19:53

#6965

Author: Bernard Fouche
Date: Wed, 27 Jan 1993 19:53

29 lines
1544 bytes

Hi wizards!

I run many applications that need to call very often the time(2)
system call. I do not see how I could design my programs to do without
having to get the result of time(2) very ofen.

But I wonder if there is a way (on a 486 running Dell Unix 2.0 at
least) to get time information without having to do a system call each
time.

For instance, does someone know if I can get a pointer toward the
value of time that is stored somewhere in the system ? Of course this
should work with processes having no suid bit set nor running as root
and files like /unix or /dev/kmem must stay to be not readable by
anyone :-)

Or am I going the wrong way because the time(2) system call is so
light that I should try to find other means to reduce the impact of my
applications on the system ?

Any comment or hint welcome !

	Thank you !
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Bernard Fouche  VOX   : +(33) (1) 48.04.56.30  FAX :  (33) (1) 48.04.98.95
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Re: How to avoid calling time(2)

#6967

Author: Gord Cody
Date: Thu, 28 Jan 1993 13:26

31 lines
1831 bytes

In <1993Jan27.195309.15120@cpio1.fr.mugnet.org> bernard@cpio1.fr.mugnet.org (Bernard Fouche) writes:

>Hi wizards!

>I run many applications that need to call very often the time(2)
>system call. I do not see how I could design my programs to do without
>having to get the result of time(2) very ofen.

>But I wonder if there is a way (on a 486 running Dell Unix 2.0 at
>least) to get time information without having to do a system call each
>time.

Every time you do a system call you are giving UNIX a chance
to swap your process.

>For instance, does someone know if I can get a pointer toward the
>value of time that is stored somewhere in the system ? Of course this
>should work with processes having no suid bit set nor running as root
>and files like /unix or /dev/kmem must stay to be not readable by
>anyone :-)

How about this. Each process attaches to a small shared memory
segment when they start. 1 process has an alarm go off every
second, it does the time() call and updates the shared memory.
Whenever any other process requires the time, it simply uses the
shared memory value. No setuid required, or running as root, or
touching of /unix or /de/kmem required. Have a nice day :)

Gord Cody - all opinions are MINE,MINE,MINE #$@%^#!##:^)  gcody@gandalf.ca
Gandalf Mobile Systems Inc. - the company has its own     613-723-6500 x 8817
2 Gurdwara Rd. Nepean Ont. Can.  - #define  th_th_th_thats_all_folks  }

Re: How to avoid calling time(2)

#6963

Author: Arlie Davis
Date: Thu, 28 Jan 1993 15:41

13 lines
1164 bytes

gcody@gandalf.ca (Gord Cody) writes:

> How about this. Each process attaches to a small shared memory
> segment when they start. 1 process has an alarm go off every
> second, it does the time() call and updates the shared memory.
> Whenever any other process requires the time, it simply uses the
> shared memory value. No setuid required, or running as root, or
> touching of /unix or /de/kmem required. Have a nice day :)

You're kidding, right?

-- 
lrwx------   1 aldavi01 emacsstu       9 Jun  6 12:43 .signature -> /dev/null

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