Re: Horrible ftruncate performance

From: Hans Reiser <reiser@namesys.com>
To: "Dieter Nützel" <Dieter.Nuetzel@hamburg.de>
Cc: Chris Mason <mason@suse.com>, ReiserFS List <reiserfs-list@namesys.com>
Subject: Re: Horrible ftruncate performance
Date: Wed, 23 Jul 2003 17:39:16 +0400	[thread overview]
Message-ID: <3F1E9004.6040800@namesys.com> (raw)
In-Reply-To: <200307231425.17476.Dieter.Nuetzel@hamburg.de>

Dieter Nützel wrote:

>Am Dienstag, 22. Juli 2003 20:09 schrieb Hans Reiser:
>  
>
>>Chris Mason wrote:
>>    
>>
>>>On Tue, 2003-07-22 at 12:43, Hans Reiser wrote:
>>>      
>>>
>>>>The answer to the below is to use reiser4.  It uses extents, and two 64
>>>>bit numbers are all that is needed to store the hole.  V4 will be ready
>>>>for testing in a few days, and will ship for real users at the end of
>>>>summer we hope.
>>>>
>>>>Fixing V3 is  the wrong answer: this is one of its design flaws.
>>>>        
>>>>
>>>It's important to remember that releasing v4 doesn't automatically
>>>convert all existing v3 users to it.  This is the kind of thing we
>>>should try to fix without making major design changes to v3.  It's at
>>>least worth talking about, "use v4" can't always be the answer.
>>>      
>>>
>>V3 is in feature freeze.   Unfortunately, determining what is a feature
>>and what is a bug is a process based not just on the user experience,
>>but on the structure of the code.  The proper fix for this bug is to add
>>a feature called extents.   This  belongs in, and is in, V4.  V4 will be
>>available very soon.
>>    
>>
>
>And "coplete" stable from the beginning? --- Come on.
>
I have been consistently clear in everything I say that V4 will not be 
as stable as V3 for quite some time.  That is because V3 will not 
significantly change except for bug fixes, whereas V4 is fresh new code.

V3 has been dropping in bug reports for quite some time.  Unfortunately 
I have to say we got some this month (direct IO stuff).

>
>  
>
>>Adding features, like new kinds of items, will disturb the stability of
>>V3.  V3 needs to be zero defect.  It is now in a phase in its lifetime
>>where conservatism is appropriate.
>>    
>>
>
>I'll accept this fix in V3 before I "move" to V4.
>
>-Dieter
>
>
>
>  
>
Most users need for their filesystems to at some point finally get left 
alone and not disturbed.  This is the whole idea behind freeze and 
release based development.

Extents are a nice feature, but they belong in V4 not V3.   Effort spent 
developing extents for V3 is better spent stabilizing V4 which already 
has them and a lot more.

-- 
Hans