lkml.org 
[lkml]   [2006]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Proposal and plan for ext2/3 future development work
Joel Becker wrote:
> On Fri, Jun 30, 2006 at 10:13:06AM -0700, Badari Pulavarty wrote:
>> I tried adding "delayed allocation" for ext3 earlier. Yes. VFS level
>> infrastructure would be nice. But, I haven't found much that we can
>> do at VFS - which is common across all the filesystems (except
>> mpage_writepage(s) handling). Most of the stuff is specific to
>> filesystem implementation (even though it could be common) - coming
>> out with VFS level interfaces to suite all the different filesystem
>> delalloc would be *interesting* exercise.
>
> Well, to be fair, I'm just going by what little I know about
> XFS. They maintain a cache of all pages waiting on delayed allocation
> for writepack. Why have this entire cache (hash, list, whatever) when
> we could create some state on in the pagecache? We save a large chunk
> of memory and some complex writeback code. I suspect you were thinking
> of this when you said "mpage_writepage(s) handling". But this is a
> large complexity win if we can do it.


No, XFS does not do this, when it gets asked to write out a page which is
delayed alloc, it goes and converts the delayed alloc extent to real disk
space. It then uses the page cache/buffer heads to find all the contiguous
pages which it can turn into a singe disk I/O. The code is made more complex
by other possible states for the data. The only information internal to XFS
though is its extent structures.

Steve
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-06-30 21:19    [W:0.085 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site