From: Peter Zijlstra <peterz@infradead.org>
To: Jon Tore Hafstad <jontore@gmail.com>
Cc: linux-kernel@vger.kernel.org, dhaval.giani@gmail.com,
mingo@elte.hu, tglx@linutronix.de, bbb@cs.unc.edu,
henrik@austad.us, jmc@cs.unc.edu, Jeff Dike <jdike@addtoit.com>
Subject: Re: LinSched updated to current linux kernel version
Date: Mon, 23 Nov 2009 15:08:15 +0100 [thread overview]
Message-ID: <1258985295.4531.496.camel@laptop> (raw)
In-Reply-To: <78b8ce680911181211k6c15a976u52186b5849224040@mail.gmail.com>
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).
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..
But I suspect that with KVM's gdb stub getting usable more and more
people are abandoning this.
> == Remaining Work ==
> One of the major issues right now is the hrtimers, which large
> portions of the scheduler now use. I have not decided exactly how to
> solve this issue yet,but this will be the focus of my work for the
> coming weeks.
The typical implementation would be signals using the posix timers.
Have the spin_lock_irq variants mask signals etc..
next prev parent reply other threads:[~2009-11-23 14:09 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 [this message]
2009-11-23 20:02 ` Henrik Austad
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