Boot Performance Targets for Karmic and +1
martin.pitt at ubuntu.com
Tue Jun 9 09:40:24 BST 2009
thanks for this excellent summary!
Scott James Remnant [2009-06-08 16:07 +0100]:
> The dependencies of the X server are:
> In otherwords, "udev". udev has no real dependencies other than being
> out of the initramfs.
> This means that the only thing holding us up loading X is udev, and the
> initramfs. Some encouraging work has been done to udev which I hope to
> talk about in a future mail, so really the problem is the initramfs.
> 2s Kernel and initramfs.
> This includes both, since arguably the need for an initramfs is a
> kernel implementation detail anyway (the kernel can mount the root
> filesystem itself in many circumstances)
I think there's one important piece missing here: readahead. Right now
we do that in a single big chunk, right after initramfs. On my box it
takes about 7 seconds; I guess it's faster on your's, but it would
still not even closely fit into the 2s + 2s second budget.
Can we sensibly split readahead to read the X bits first, and then
everything else in a second block? This might not be relevant with
sreadahead and SSDs (since stuff gets read in usage order), but is a
problem on rotary disks (where readahead reads them in disk block
Martin Pitt | http://www.piware.de
Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org)
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