Date:         Wed, 30 Oct 2002 13:27:13 -0800
Reply-To:     "Huang, Ya" <ya.huang@PFIZER.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Huang, Ya" <ya.huang@PFIZER.COM>
Subject:      Re: Sleep Function for NON WINDOWS OS
Comments: To: "Cassell.David@EPAMAIL.EPA.GOV" <Cassell.David@EPAMAIL.EPA.GOV>
Content-Type: text/plain

Thanks David,

Ian in a private response also pointed the same thing.
Now what I am not sure is that, obviously when a real
sleep() is running, you can't execute the subsequent
statement, therefore it makes no difference from my
fake sleep(), because anyway you have to wait, no matter
SAS take too much CPU time or not. On the other hand,
if a real sleep() function really does not take much
cpu time, OS might be smart enough to allocate the CPU
time to other application. I'm not sure if VMS will
grab the spare time from SAS and give to other application,
my understanding to old VMS system is that how much time
slot one application can get, depends on the priority of
the job, which is pretty much defined before you run
the job, therefore, a job can't really get the other's
job's cpu time even it is in 'idle'. I don't believe
that's the case any more for open VMS.

I wonder if someone can do a test to see how big a difference
there is. It seems to me for Windows, I can run my
fake sleep and in the meantime run IE browser and outlook
email without noticing significant slow down.

Comments?

Thanks

Ya


-----Original Message-----
From: David L. Cassell [mailto:Cassell.David@EPAMAIL.EPA.GOV]
Sent: Wednesday, October 30, 2002 1:05 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Re: Sleep Function for NON WINDOWS OS


"Huang, Ya" <ya.huang@PFIZER.COM> replied [in part]:
> Here is a simple macro, you may use it as a sleep function:
>
> 73   %macro sleep(sec=);
> 74    data _null_;
> 75     t1=time();
> 76     do until(t2-t1 >= &sec);
> 77     t2=time();
> 78     end;
> 79     run;
> 80   %mend;

While this will make the OS wait for SEC seconds, it isn't really a
sleep() function.  It makes the OS burn cpu cycles, rather than just
waiting a set amount of time to re-start.

If Charles really needs an OS-independent option, then I would
suggest using the X command and Perl, which *does* run on
Open MVS with the same sleep() function that it has on every other
platform.

David
--
David Cassell, CSC
Cassell.David@epa.gov
Senior computing specialist
mathematical statistician