Messages in this thread | | | Subject | Re: [STATUS 2.5] May 1, 2002 | From | (Eric W. Biederman) | Date | 01 May 2002 21:14:27 -0600 |
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Stephen Lord <lord@sgi.com> writes:
> On Wed, 2002-05-01 at 16:38, Andrew Morton wrote: > > Mike Fedyk wrote: > > > > > > On Wed, May 01, 2002 at 09:53:37AM -0400, Guillaume Boissiere wrote: > > > > new framebuffer layer, as well as some more delayed disk block > > > > allocation bits. > > > > > > Actually Andrews work on address_space based writeback is related somewhat, > > > but really it's a rewrite/cleanup of the buffer layer. Delayed block > > > alocation is helped alot by this, and almost depends on it IIRC. > > > > > > One vote for a seperate listing in the status for "Address Space based > > > Writeback / Buffer layer cleanup". > > > > Well the next major step here is going direct > > pagecache<->BIO, bypassing the intermediate submit_bh > > for most I/O. > > > > Probably that will make most of the performance benefits > > of delayed-allocate go away. > > Most of the performance benefits of delayed allocate are that > you do not the hard work of allocating the disk space in each > write call, you get to do it once, in potentially larger chunks, > and often not in the user's context.
Except for moving the work out of the users context, ext2 gets a similar benefit by reserving disk space ahead of time. So it isn't clear that you need to have a delayed allocation to achieve this.
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