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Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN

Previous thread: Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN by strangepics on Sunday, June 15, 2008 - 2:41 am. (1 message)

Next thread: Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN by Matthew Dillon on Monday, June 16, 2008 - 10:53 am. (1 message)
[view original message]
From: Matthew Dillon <dillon@...>
To: <kernel@...>
Subject: Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN
Date: Sunday, June 15, 2008 - 10:28 pm

I am not too familiar with Reiser so I can't really come to that

    conclusion, but it doesn't seem likely that the reasons are similar.


    HAMMER's issue insofar as the B-Tree goes is mainly due to its history

    retention practices.  If I mount with -o nohistory then the issue

    becomes one of locality of reference due to HAMMER not immediately

    reusing space freed by the rename-over that blogbench does.


    After running the test over the weekend the culprit seems to pointing

    more towards HAMMER's low level storage allocation model and away

    from the B-Tree per-say.  I was already planning on making some major

    changes there so we'll see what pans out.


					-Matt

					Matthew Dillon

					<dillon@backplane.com>
[view original message]
From: Dan M <strangepics@...>
To: <kernel@...>
Subject: Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN
Date: Monday, June 16, 2008 - 4:18 pm

On Sun, Jun 15, 2008 at 10:28 PM, Matthew Dillon


They used B+ in earlier versions. In Reiser4 they decided to use


http://en.wikipedia.org/wiki/B*-tree


and


http://en.wikipedia.org/wiki/Dancing_trees


--

Dan
[view original message]
From: Thomas Zander <thomas.e.zander@...>
To: <kernel@...>
Subject: Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN
Date: Monday, June 16, 2008 - 12:50 am

On Mon, Jun 16, 2008 at 10:28 AM, Matthew Dillon


Maybe the question is why B+ trees are so popular in current file

systems. I am certainly not expert enough to see all the implications

of the selection of the tree structure on the implementation and

performance of a file system, but what is the main reason why you

chose B- trees?


Riggs
Previous thread: Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN by strangepics on Sunday, June 15, 2008 - 2:41 am. (1 message)

Next thread: Re: HAMMER Update 13-June-2008 - HEADS UP: MEDIA CHANGED AGAIN by Matthew Dillon on Monday, June 16, 2008 - 10:53 am. (1 message)