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DragonFly kernel List (threaded) for 2011-03
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Re: A question on gsoc2011 schedule and how the mentoring works.

From: Nohhyun Park <parkx408@xxxxxxxxx>
Date: Tue, 29 Mar 2011 13:38:33 -0500

Yes, I have thought about the issue (though not for the reasons you mentioned).
In fact I have already included in proposal that LIRS should be
implemented first. (Not because of patent but simply because Linux
kernel already implements it.)
Would implementing ARC be a problem for opensource projects as well?
(Content based chunking using Rabin's fingerprint is also patented but
people use it in opensource project all the time.)

I was thinking to make the vnode list management as part of mount time
option and allow different algorithms to be used.
If the LIRS is the only target than maybe I should just extend current
LRU implementation since LIRS should always out perform LRU.

So I guess my questions is;
1. Is there any value in making vnode list management as mount time option?
2. What about algorithms like CLOCK-pro
(http://citeseerx.ist.psu.edu/viewdoc/summary?doi= which
was used before LIRS and can out perform LIRS at some algorithmic
3. Perhap the most important questions is (I have asked this one
before but no one replied), how critical is vnode management in terms
of overall performance? Any specific application domain where this
would become the bottleneck?

I would still like to implement ARC just to compare it's performance
with other algorithm. (I am a graduate student and I need to convince
my advisor that this project will result in a paper or two)
Thank you.



On Tue, Mar 29, 2011 at 9:47 AM, Samuel J. Greear <sjg@evilcode.net> wrote:
> On Tue, Mar 29, 2011 at 8:39 AM, Alex Hornung <ahornung@gmail.com> wrote:
>> On 29/03/11 07:02, Nohhyun Park wrote:
>>> Hi.
>>>  I am a student hoping to work on the "Implement ARC algorithm
>>> extension for the vnode free list" project.
>> Have you given this some thought? ARC is a patented algorithm and I'm
>> not sure it's the greatest idea to implement[1], knowingly, a patented
>> algorithm.
>> I think you should discuss your thoughts here on this list more before
>> putting your application forward. Maybe someone else can provide some
>> other algorithm with similar performance to ARC, yet not patent encumbered.
>> Kind Regards,
>> Alex Hornung
>> [1]: http://www.varlena.com/GeneralBits/96.php
> LIRS -> http://www.cse.ohio-state.edu/hpcs/WWW/HTML/publications/papers/TR-02-6.pdf
> was suggested as a possible alternative on IRC.
> Best,
> Sam


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