# Re: \[PATCH v3 0/5\]add new ioctls to do metadata readahead in btrfs

- From: Shaohua Li \<hidden\>
- Date: 2011-01-20 02:27:13 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2011/01/50431
- Thread: https://ratatoskr.run/linux-api/2011/01/50349/t.md

```text
On Thu, 2011-01-20 at 05:33 +0800, David Nicol wrote:
> On Wed, Jan 19, 2011 at 2:34 PM, Andrew Morton
> [ref] wrote:
> 
> > It would be much more valuable if those 3.5 seconds were available to
> > devices which really really care about bootup times, but very few of
> > those devices use rotating disks nowadays, I expect?
> 
> And don't rotating disk modules read and buffer whole tracks, doing
> their own readahead, anymore, anyway? Isn't that part of what "on-disk
> cache" does?
The disk readahead and the metadata readahead is completely different,
you didn't even look at the patch or log before saying this.
```