BOUNCE rtl@rtlinux.org: Approval required: Non-member submission from [Thomas Folkers <tfolkers@hamms.as.arizona.edu>] (fwd)

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>From owner-rtl Fri May  4 10:13:04 2001
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To: yodaiken@hq2.fsmlabs.com
cc: rtl@fsmlabs.com, tfolkers@hamms.as.arizona.edu
Subject: Re: [rtl] do_gettimeofday(). 
In-Reply-To: Message from yodaiken@hq2.fsmlabs.com 
   of "Thu, 03 May 2001 14:42:52 CST." <20010503144252.A3275@hq2> 
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Date: Fri, 04 May 2001 09:09:04 -0700
From: Thomas Folkers <tfolkers@hamms.as.arizona.edu>

Victor,
  I downloaded the release from your website. It was the latest one. Here's
what I found in the Makefile:

VERSION         = 3.0
# for the 3.0 final, set PRERELEASE to 100
PRERELEASE      = 100

  I am running this on a 650 MHz Pentium III:

% cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 8
model name	: Pentium III (Coppermine)
stepping	: 3
cpu MHz		: 654.588
cache size	: 256 KB
fdiv_bug	: no
hlt_bug		: no
sep_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 3
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 
psn mmx fxsr xmm
bogomips	: 1307.44


% uname -a

Linux smtdbe 2.2.18-rtl #6 SMP Wed May 2 14:58:37 MST 2001 i686 unknown


Hope this answers you questions.

Thanks,
Tom


>
> What version of RTL and what processor has the time gain?
> clock_gettime is better than do_gettime since it is 
> the POSIX call and will work on RTbsd as well as RTLinux. 
> We should just fix the gettime if that's not correct.
>
>
> > Thomas Folkers wrote:
> > > 
> > > Victor,
> > >   How come I can't get the time of day from the kernel? If I use
> > > do_gettimeofday(), eventually the system will hang. It may not happen
> > > right away, but it will hang. I'm trying to time external events and
> > > record the exact time an interrupt comes in and the only way to compare
> > > that time to other events and to other systems is to have the exact
> > > system time. The clock_gettime() routine returns something close to
< > > the real system clock time, but then proceeds to gain time at the rate of
> > > 35,000 nsecs/sec. That's probably due to a miss calibration in the cpu HZ
> > > value. I have looked over the rtl_time.c file and can see where you 'sync'
> > > the CLOCK_REALTIME to the results of a do_gettimeofday() call, but then
> > > there doesn't seem to be any other 'tweeks' to the time to keep it in
> > > sync. So, while the clock_gettime() produces a nice monotonic clock, it
> > > bear little resemblance to actual time.
> > >   So, how do I get the time of day from the kernel?
> > > 
> > > Thanks for you help,
> > > Tom
> > > 

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