From: Amit Kapila <amit.kapila@huawei.com>
To: "'Ants Aasma'" <ants@cybertec.at>
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Subject: Re: Improvement of checkpoint IO scheduler for stable transaction
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Date: Thu, 18 Jul 2013 16:50:43 +0530
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On Wednesday, July 17, 2013 6:08 PM Ants Aasma wrote:
> On Wed, Jul 17, 2013 at 2:54 PM, Amit Kapila <amit.kapila@huawei.com>
> wrote:
> > I think Oracle also use similar concept for making writes efficient,
> and
> > they have patent also for this technology which you can find at below
> link:
> >
> http://www.google.com/patents/US7194589?dq=645987&hl=en&sa=X&ei=kn7mUZ-
> PIsWq
> > rAe99oDgBw&sqi=2&pjf=1&ved=0CEcQ6AEwAw
> >
> > Although Oracle has different concept for performing checkpoint
> writes, but
> > I thought of sharing the above link with you, so that unknowingly we
> should
> > not go into wrong path.
> >
> > AFAIK instead of depending on OS buffers, they use direct I/O and
> infact in
> > the patent above they are using temporary buffer (Claim 3) to sort
> the
> > writes which is not the same idea as far as I can understand by
> reading
> > above thread.
> 
> They are not even sorting anything, the patent is for
> opportunistically looking for adjacent dirty blocks when writing out a
> dirty buffer to disk. While a useful technique, this has nothing to do
> with sorting checkpoints. 

It is not sorting, rather it finds consecutive blocks before writing to disk
using hashing in buffer cache.
I think the patch is different from it in multiple ways.
I had read this patent some time back and thought that you are also trying
to achieve something similar (Reduce random I/O), 
so shared with you.

With Regards,
Amit Kapila.


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