[QA] Release Meeting 2011-12-09

[Steve Langasek]

Hi Patrick,

On Mon, Dec 12, 2011 at 08:16:16AM -0700, Patrick Wright wrote:
> >> On Fri, Dec 09, 2011 at 09:34:43AM +0100, Jean-Baptiste Lallement wrote:

> >>>  * Boot Speed testing
> >>>    * Daily boot speed testing run on Desktop i386
> >>>    * Report: http://reports.qa.ubuntu.com/reports/boot-speed/

> >> Today's test for the Dell Vostro shows that ureadahead is not preloading
> >> files as intended:

> >> http://reports.qa.ubuntu.com/reports/boot-speed/dell-vostro-3400/2011-12-09_09-59-00/bootchart.png

> >> This could be due to either a bug in ureadahead or a bug in the test
> >> configuration.  (It does not appear to be caused by using an SSD; looking
> >> at
> >> the device name listed in dmesg, this seems to be a rotational disk model.
> >> It would probably be helpful if this information were easily visible in
> >> some
> >> sort of summary of the machine information.)
> If the info you require isn't listed in lspci file please provide me
> with what specific data would be helpful to add. Providing the command
> with options would be most helpful to me.

Presumably you have information about the machines to know if the disks are
rotational or SSD, but it's non-trivial to extract it from the system logs,
which is why it would be useful to have it listed directly in the report
somewhere.  It certainly wouldn't be listed in lspci (the disk is not a pci
endpoint); the disk model is listed in the dmesg output, but it requires a
google search from there to figure out what that disk is.  If there's a way
to automatically tell from the kernel if a disk is an SSD, I don't know it.

> >> Is the methodology used for boot speed testing described somewhere?  I'd
> >> like to try to reproduce this and figure out what's happening.  Not having
> >> ureadahead working correctly causes a huge amount of noise in boot charts;
> >> for instance, today's chart shows lightdm hitting the disk for a full
> >> second
> >> before it gets around to starting X (which gets counted against the
> >> plumbing
> >> budget), and this almost entirely accounts for the difference in plumbing
> >> time in yesterday's run vs. today's on this machine.  There's no way to
> >> tell from the currently available info if this is a regression in lightdm,
> >> or just noise as a result of ureadahead not running correctly.

> Automation aside, its really simple if you want to do this manually.
> 1. Get the latest daily iso (desktop or alternate)
> 2. Install from iso
> 3. Install bootchart package on startup
> 4. Reboot again
> 5. Check bootchart results

Thanks, having this spelled out is useful, because there's a bug in this
methodology. ;)  You must reboot *twice* after installing the bootchart
package, because the act of installing bootchart invalidates the ureadahead
packs on the filesystem (/var/lib/dpkg/info/ureadahead.triggers, .postinst). 
So the first reboot after installing the bootchart package is a ureadahead
profiling run with ureadahead not actually doing anything to help boot
speed; then on a second reboot, ureadahead has a pack available that it can
use for measuring.

Please reboot twice after installing bootchart, as part of all the boot
speed tests.

> You can add debugging to dmesg if that will provide information useful to
> you.

Well, given that my primary interest is the "Plumbing" timing, dmesg is not
necessarily the most useful log for me :)

Cheers,
-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 828 bytes
Desc: Digital signature
URL: <https://lists.ubuntu.com/archives/ubuntu-release/attachments/20111212/9119e86a/attachment.pgp>