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From: Michael Reinelt <reinelt@eunet.at>
To: george anzinger <george@mvista.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: nanosleep question
Date: Sun, 11 Mar 2001 12:20:47 +0100	[thread overview]
Message-ID: <3AAB5F8F.D93E5B47@eunet.at> (raw)
In-Reply-To: <3AA607E7.6B94D2D@eunet.at> <3AA936B2.D2F26847@mvista.com> <3AA9D575.1345EF2@eunet.at> <3AA9FBD7.A3EDD325@mvista.com>

george anzinger wrote:
> > > > At the moment I implemented by own delay loop using a small assembler
> > > > loop similar to the one used in the kernel. This has two disadvantages:
> > > > assembler isn't that portable, and the loop has to be calibrated.
> > >
> > > Why not use C?  As long as you calibrate it, it should do just fine.
> > Because the compiler might optimize it away.
> 
> Not if you use volatile on the data type.
I did a lost of testing and experimenting, and found the assembler loop
the best solution (it has the finest granualrity even on slower
systems).

> > > the other hand, since you are looping anyway, why not loop on a system
> > > time of day call and have the loop exit when you have the required time
> > > in hand.  These calls have microsecond resolution.
> > I'm afraid they don't (at least with kernel 2.0, I didn't try this with
> > 2.4).
> 
> Gosh, I started with 2.2.14 and it does full microsecond resolution.

Oh! Shame on me! I must have missed something here!

I could swear that this didn't work for me. I tried it yesterday, you
are right, there is microsecond resolution. Even on an old 2.0.38
kernel...

This solves all my problems. I'll loop on gettimeofday().

Thanks a lot!

                 Michael

-- 
netWorks       	                                  Vox: +43 316  692396
Michael Reinelt                                   Fax: +43 316  692343
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A-8045 Graz, Austria			      e-mail: reinelt@eunet.at

      reply	other threads:[~2001-03-11 11:22 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-03-07 10:05 nanosleep question Michael Reinelt
2001-03-09 20:01 ` george anzinger
2001-03-10  7:19   ` Michael Reinelt
2001-03-10 10:03     ` george anzinger
2001-03-11 11:20       ` Michael Reinelt [this message]

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