From: Henrik Austad <henrik@austad.us>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jon Tore Hafstad <jontore@gmail.com>,
linux-kernel@vger.kernel.org, dhaval.giani@gmail.com,
mingo@elte.hu, tglx@linutronix.de, bbb@cs.unc.edu,
jmc@cs.unc.edu, Jeff Dike <jdike@addtoit.com>
Subject: Re: LinSched updated to current linux kernel version
Date: Mon, 23 Nov 2009 21:02:03 +0100 [thread overview]
Message-ID: <200911232102.07419.henrik@austad.us> (raw)
In-Reply-To: <1258985295.4531.496.camel@laptop>
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On Monday 23. November 2009 15.08.15 Peter Zijlstra wrote:
> On Wed, 2009-11-18 at 21:11 +0100, Jon Tore Hafstad wrote:
> > Hi all
> >
> > I wish to inform you about an update of LinSched (The Linux Scheduler
> > Simulator([1])) I'm currently working on.
> >
> > == Motivation ==
> > I wished to implement different EDF schedulers to gain a better
> > understanding of kernel internals as well as scheduling dynamics. I
> > got some feedback from Henrik Austad that LinSched was a tool that
> > made implementing a scheduler in to the linux kernel easier, since
> > the code compiles in a fraction of the time the kernel does (Yes, I
> > know you can pull all sorts of tricks and tweaks in order to speed up
> > a kernel compilation), a segfault will be a segfault, and not a kernel
> > oops ;),and the full range of debuggers and memory analyzers will be
> > available.
>
> I would have expected people to use UML for this (User-Mode-Linux, not
> the draw lots of silly pictures thing).
What is the current status of UML - is anyone actually working on that these
days?
> The main draw-back is that UML doesn't currently support SMP and any
> interesting preemption modes, but adding that to UML would help out more
> people -- I know the VM (virtual Memory, not the machine thing) people
> used to use UML for exactly these reasons, easy gdb, etc..
Well, another drawback of UML is the size. The whole point with LinSched is to
be *lightweight* while still being accurate. By accurate I mean that code
written and tested with LinSched should work nearly out of the box when placed
in the kernel.
LinSched is all about scheduling - nothing else. To be able to compile the
code in a fraction of a second, and then simulate hours worth of computing (or
at least the task-switches) can be *very* useful.
IMHO, making it easy to test new scheduling algorithms is a very neat way of
attracting new kernel/scheduler hackers (as well as testing all sorts of crazy
algorithms).
Just my $0.02
--
henrik
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prev parent reply other threads:[~2009-11-23 20:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-18 20:11 LinSched updated to current linux kernel version Jon Tore Hafstad
2009-11-23 14:08 ` Peter Zijlstra
2009-11-23 20:02 ` Henrik Austad [this message]
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