From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@linaro.org (Kevin Hilman) Date: Thu, 14 Feb 2013 15:08:02 -0800 Subject: Porting 3.8-rc4-nohz3 to ARM (PandaBoard) In-Reply-To: <20130211190317.GA8513@enea.se> (Mats Liljegren's message of "Mon, 11 Feb 2013 20:03:17 +0100") References: <20130204200238.GA16718@enea.se> <20130211190317.GA8513@enea.se> Message-ID: <874nhea3zh.fsf@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Mats Liljegren writes: > Frederic Weisbecker wrote: >> 2013/2/4 Mats Liljegren : >> > Hi Frederic, >> > >> > (Sorry for the re-post, I spelled the mailing list wrong...) >> > >> > I want to port dynticks patches 3.8-rc4-nohz3 to ARM architecture, >> > and try it out on the PandaBoard. Initially this is for evaluating >> > it, but if it looks promising I'd like to upstream this. >> > >> > As far as I can see the first thing to do is to implement virtual >> > time accounting. After an initial look at the patches done for >> > ia64, it doesn't look too difficult. >> >> No that part is handled by the core code. But you need to implement >> the context tracking arch backend. >> Here is what Li Zhong did to port it on Powerpc for example: >> https://lkml.org/lkml/2013/2/1/216 >> >> > Are there any caveats I should be aware of? >> >> The generic cputime accounting only works on 64 bits archs. We'll need >> to do some safe accessors to read the kernel_stat. In the meantime you >> can do home tests by removing the CONFIG_64BIT dependency. This >> shouldn't be dangerous >> >> > Has anyone else started any work in this area that I could co-operate with? >> >> Yeah two people have been working on this. But it was several month >> ago and I haven't hear from them since then. I'm adding Geoff in Cc. I >> can't retrieve the other guy who has worked on it too. > > Could the other guy be Kevin Hillman? Yup, that's him (though my last name has only one 'l' ;) > The name has been mentioned to me but I don't have his e-mail address. Now you do. :) After some time away, I'm back to working on getting adaptive nohz working on ARM, but things have changed quite a bit since I last worked on it. Things actually look a bit simpler now with the new context_tracking layer, but that needs a little work for ARM which I'm now looking into. However, just to get things compiling needs a little work too. I've setup a work-in-progress branch which you can start from to at least get things compiling[1]. I noticed you already ran accross the 64-bit division problem. I've proposed a patch for that[2] which is included in my branch along with a few other things. Hope that helps, Kevin [1] git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux.git wip/3.8-rc6-nohz4-arm [2] http://marc.info/?l=linux-kernel&m=136087139214252&w=2