[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-ext4
Subject:    [Ext2-devel] Re: [lkml FW]: ext3 reservation strangeness?!
From:       Mingming Cao <cmm () us ! ibm ! com>
Date:       2004-10-26 22:27:33
Message-ID: 1098829656.8919.7604.camel () w-ming2 ! beaverton ! ibm ! com
[Download RAW message or body]

On Tue, 2004-10-26 at 13:02, karl.vogel@seagha.com wrote:
> Mingming Cao <cmm@us.ibm.com> writes:
> 
> > 1) ext3_find_goal() randomly(based on the pid) select a goal block for
> > the very first block to allocate. It is possible that ext3_find_goal
> > generate a bad start for the reservation case-- the bitmap around the
> > goal block has a lot of other files already allocated. But for the
> > non-reservation case, it picked up a good place to place the file, there
> > is no(or only a few) other files nearby. I don't know if we could do
> > something here.
> 
> I don't know the ext3 code, but I thought that the actual allocation only
> happened at the write out moment?! So my understanding was that if I 
> copied the 8mb file (which can be cached entirely in memory), that it
> would be allocated on disk when it was actually written out and with
> enough diskspace available, it should be possible to find a place on
> disk that could fit the file without fragments. (that's also why I raised
> the commit time, as I thought it caused the allocation to occur faster).
> 
> Or is this not the way it works?!
> 
I thinking you are talking about delayed allocation -- it is missing in
ext3. Currently the block is allocated before it is actually written out
to disk. 



-------------------------------------------------------
This SF.Net email is sponsored by:
Sybase ASE Linux Express Edition - download now for FREE
LinuxWorld Reader's Choice Award Winner for best database on Linux.
http://ads.osdn.com/?ad_id=5588&alloc_id=12065&op=click
_______________________________________________
Ext2-devel mailing list
Ext2-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ext2-devel
[prev in list] [next in list] [prev in thread] [next in thread]