Re: [PATCH] stopmachine: add stopmachine_timeout

On Monday 14 July 2008 21:51:25 Christian Borntraeger wrote:

Am Montag, 14. Juli 2008 schrieb Hidetoshi Seto:

quoted

+	/* Wait all others come to life */
+	while (cpus_weight(prepared_cpus) != num_online_cpus() - 1) {
+		if (time_is_before_jiffies(limit))
+			goto timeout;
+		cpu_relax();
+	}
+

Hmm. I think this could become interesting on virtual machines. The
hypervisor might be to busy to schedule a specific cpu at certain load
scenarios. This would cause a failure even if the cpu is not really locked
up. We had similar problems with the soft lockup daemon on s390.

5 seconds is a fairly long time.  If all else fails we could have a config 
option to simply disable this code.

It would be good to not-use wall-clock time, but really used cpu time
instead. Unfortunately I have no idea, if that is possible in a generic
way. Heiko, any ideas?

Ah, cpu time comes up again.  Perhaps we should actually dig that up again; 
Zach and Jeremy CC'd.

Thanks,
Rusty.