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Date: Fri, 3 Apr 2009 23:51:12 +0900 From: Hitoshi Mitake <h.mitake@...il.com> To: Amithash Prasad <amithash@...il.com> Cc: Peter Zijlstra <peterz@...radead.org>, linux-kernel@...r.kernel.org, cpufreq@...r.kernel.org Subject: Re: [RFC] Improving scheduler for asymmetric multi-core processor in Google's summer of code On Fri, Apr 3, 2009 at 01:46, Amithash Prasad <amithash@...il.com> wrote: > Yes, I have something similar up going towards my master's thesis. > But in the beginning I chose to have it as a kernel module rather than in > the kernel, and as a direct consequence, it is a mess with kprobes > everywhere. > And as Peter mentioned it is very delicate. I have not even touched on all > possible aspects and not a bit proud about my code. I will have more > detailed performance graphs, and my defense is in 2 weeks. Once that is > over, I will share the results with you. > As far as I have noticed, the scheduler does have NUMA support. It's wonderful for me. I'm looking forward to watching your result. More power to you! > > On Thu, Apr 2, 2009 at 5:53 AM, Hitoshi Mitake <h.mitake@...il.com> wrote: >> >> On Thu, Apr 2, 2009 at 20:13, Peter Zijlstra <peterz@...radead.org> wrote: >> > On Wed, 2009-04-01 at 23:58 +0900, Hitoshi Mitake wrote: >> >> Hi, >> >> >> >> I found an interesting problem, scheduling on Asymmetric multi-core >> >> processor. >> >> >> >> According to this paper, >> >> >> >> >> >> http://portal.acm.org/citation.cfm?id=1362694&dl=GUIDE&coll=GUIDE&CFID=28487975&CFTOKEN=68150071 >> >> >> >> taking performance asymmetry into consideration on multi-core CPUs can >> >> improve scheduler performance. >> >> (And I think discarding this could have bad consequences.) >> >> >> >> So I have a question: >> >> Is the current scheduler of Linux aware of possible performance >> >> asymmetry of the cores? >> > >> > It does not. >> > >> >> By performance asymmetry I mean a case where different cores run on >> >> different frequencies. >> >> >> >> If something tackling this issue is not implemented yet, >> >> I would like to work on that as a project of Google's summer of code. >> > >> > Have at it. >> > >> > Its a rather delicate business though and should also include scaling >> > balancing decisions based on time taken by IRQs and RT tasks as well as >> > incorporate feedback from the cpu. The latter includes things like >> > cpufreq, but also effective work done by threads on a core. >> > >> > Its been on my todo list for quite a while, but haven't managed to get >> > something robust together. >> > >> >> Amithash and Peter, >> >> I evaluated the performance of Linux on ASMP. >> I made web page to describe this: >> http://www.dcl.info.waseda.ac.jp/~mitake/asmp/ >> because I want to use some pictures for easy to read. >> (Sorry for my broken English! I'm Japanese and not good at English.) >> >> And it seems that there's no problem at least on my evaluation. >> So I can't define problem clearly now. I pass this year's >> GSoC.(Deadline is coming soon.) >> >> But I'll continue to research ASMP as a private project. >> As Peter told, this is delicate business. >> For example, this may be more difficult problem when realtime task exists. >> (Setting frequency low may be fatal for deadline of RT tasks.) >> >> Thanks a lot! >> >> Hitoshi > > > > -- > Amithash E. Prasad > ECE Department, CU > http://eces.colorado.edu/~prasadae > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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