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
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prev parent 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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