Re: Linux 2.4.13-ac1

[Alan Cox]

> simply because the <2.4.10 buffer cache layer wasn't able to do proper
> readahead on the blkdev. Now we do readahead properly and so in turn
> the the lack of media-change trust of the vfs shows up. So as far I can
> tell the right fix have no influence on the blkdev in pagecache, but it
> only consists in resurrecting the media-change detection with a
> per-device bitflag whitelist. I cannot see other source of stalls across
> a close/open cycle.

I'm not currently sure if the impact is from the cost of the page cache
flushing or the invalidate/re-read it triggers. There probably are two or
three seeks on the DVD if the data is invalidated so that would make sense.

Alan