BootChart

Introduction

Bootchart is a tool for performance analysis and visualization of the GNU/Linux boot process. In December 2009 it was added to the daily live-cd builds for early alpha armel images in the hope that it would help determine what the main causes of slowness were. The following information is the results of that investigation.

BootChart Visual

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  Click the image for a larger view (Size: 401k)

BootChart Analysis

From analysing the above BootChart information the following conclusions can be drawn:

• The CPU is utilised nearly 100% for the full boot process.
• The Casper process takes around 110 secs of the total 195 secs to boot so speeding up Casper will give a large overall speedup.

• debconf-communicate stands out as a cause of much slowness. This is confirmed by the investigations done with Casper which can be found here.

• disable_guest_user's call to dpkg is another cause of slowness.
• debconf-set-sel should be investigated.
• MAKEDEV and the mountall process take nearly 12 seconds to complete.

From looking at the bootchart information it is clear that Casper is the source of slowness. After Casper has completed there is little delay for the rest of the boot and one can conclude that the effort to speed up this process should be targeted entirely at Casper.