linux-kernel - Re: Status on CPU hotplug issues

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Message-ID: <20061007102419.GB30034@elf.ucw.cz>
Date:	Sat, 7 Oct 2006 12:24:19 +0200
From:	Pavel Machek <pavel@....cz>
To:	Andrew Morton <akpm@...l.org>
Cc:	Bryce Harrington <bryce@...l.org>, vatsa@...ibm.com,
	torvalds@...l.org, linux-kernel@...r.kernel.org,
	shaohua.li@...el.com, hotplug_sig@...l.org,
	lhcs-devel@...ts.sourceforge.net
Subject: Re: Status on CPU hotplug issues

Hi!

> > > How well tested is this?  From my reading, this will cause
> > > enable_nonboot_cpus() to panic.  Is that intended?
> > 
> > I wanted to give you an update on results of cpu testing I've done on
> > recent kernels and several architectures.  Since -rc1 is out, I wanted
> > to give added visibility to the few issues that remain.
> > 
> > The full results are available here:
> > 
> >     http://crucible.osdl.org/runs/hotplug_report.html
> > 
> > This is actually a report for cpu hotplug tests generated hourly,
> > however we run it against all of the kernel -git snapshots posted to
> > kernel.org.  Whereever you see a blank square, it indicates the kernel
> > either failed to build or boot.

So... patch-2.6.18-git4 failed to boot on all architectures? I'm
seeing very little green fields there... actually I only see two green
fields in whole table.

(And it would be nice to call ia64 "ia64", not "ita64" :-)

> Can you describe the nature of the cpu-hotplug tests you're running?  I'd
> be fairly staggered if the kernel was able to survive a full-on cpu-hotplug
> stress test for more than one second, frankly.  There's a lot of code in
> there which is non-hotplug-aware.  Running a non-preemptible kernel would
> make things appear more stable, perhaps.
> 
> iirc Pavel did some testing a month or two ago and was seeing userspace
> misbehaviour?

Pavel did some testing (like two threads trying to plug/unplug cpus at
the same time), and seen machines dying real fast; but that was fixed,
IIRC, and I did not really torture it after that.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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