From: Sven-Thorsten Dietrich <sven-IsH+rWyeNGyzjR9+/8zPv5owlv4uC7bZ@public.gmane.org>
To: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Cc: Leon Woestenberg
<leon.woestenberg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
rt-users <linux-rt-users-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"Ben Dooks (embedded platforms)"
<ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>
Subject: Re: yield() in i2c non-happy paths hits BUG under -rt patch
Date: Sun, 08 Nov 2009 10:57:16 -0800 [thread overview]
Message-ID: <4AF7148C.9090706@thebigcorporation.com> (raw)
In-Reply-To: <20091107210147.3e754278-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
On 11/07/2009 12:01 PM, Jean Delvare wrote:
>
> One thing I do not understand: if yield() is a bug to RT kernels, then
> we would have to remove them all? But so far, yield() still exists in
> the kernel tree, and it serves a purpose. Are you going to ask all
> developers to remove all occurrences of yield() in their code? Doesn't
> sound terribly realistic.
>
>
The flaw in using yield() with RT priorities, is that it doesn't do what
you expect.
The scheduler will run, and pick the highest-priority thread, which is
the one yield()-ing.
So the risk is, that whatever the yield() intended to do, it won't do,
and worse, that you will end up endlessly yielding to yourself, locking
the machine.
So the call is for something more explicit of an implementation.
Sven
next prev parent reply other threads:[~2009-11-08 18:57 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-07 19:01 yield() in i2c non-happy paths hits BUG under -rt patch Leon Woestenberg
[not found] ` <c384c5ea0911071101u7415d37o2611c542e5fae309-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2009-11-07 20:01 ` Jean Delvare
[not found] ` <20091107210147.3e754278-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2009-11-08 18:57 ` Sven-Thorsten Dietrich [this message]
[not found] ` <4AF7148C.9090706-IsH+rWyeNGyzjR9+/8zPv5owlv4uC7bZ@public.gmane.org>
2009-11-12 20:12 ` Jean Delvare
2009-11-13 22:03 ` Thomas Gleixner
2009-11-14 18:02 ` Jean Delvare
[not found] ` <alpine.LFD.2.00.0911132139560.24119-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2009-11-16 15:56 ` Mark Brown
[not found] ` <20091116155606.GC29479-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2009-11-18 0:50 ` Leon Woestenberg
2009-11-18 1:05 ` Alan Cox
[not found] ` <20091118010520.4cd397d4-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2009-11-18 16:28 ` Leon Woestenberg
2009-11-18 16:52 ` Jean Delvare
[not found] ` <20091118175202.490989d8-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2009-11-18 20:36 ` Thomas Gleixner
2009-11-19 12:05 ` Jean Delvare
[not found] ` <20091119130526.23a69b85-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2009-11-19 12:59 ` Alan Cox
[not found] ` <20091119125906.6ad00edd-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2009-11-19 13:06 ` Peter Zijlstra
2009-11-19 14:00 ` Jean Delvare
2009-11-19 14:15 ` Peter Zijlstra
2009-11-19 13:11 ` Thomas Gleixner
2009-11-19 13:21 ` Peter Zijlstra
2009-11-19 13:22 ` Thomas Gleixner
2009-11-19 13:18 ` Peter Zijlstra
2009-11-18 20:46 ` [PATCH] cleanup sched_yield (sys)call nesting Sven-Thorsten Dietrich
[not found] ` <1258577194.12429.86.camel-ZUMNgey8dAdBci4yedNfAfz91O0DMRRp0E9HWUfgJXw@public.gmane.org>
2009-11-18 20:56 ` Thomas Gleixner
[not found] ` <alpine.LFD.2.00.0911182153010.24119-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2009-11-18 21:04 ` Sven-Thorsten Dietrich
2009-11-18 21:34 ` Thomas Gleixner
[not found] ` <alpine.LFD.2.00.0911182233510.24119-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2009-11-19 4:48 ` Sven-Thorsten Dietrich
[not found] ` <1258606116.25022.57.camel-ZUMNgey8dAdBci4yedNfAfz91O0DMRRp0E9HWUfgJXw@public.gmane.org>
2009-11-19 10:36 ` Thomas Gleixner
2009-11-19 3:20 ` Ingo Molnar
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