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Firefox OS/Performance/Boot Sequence Optimization: Difference between revisions
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Firefox OS/Performance/Boot Sequence Optimization (view source)
Revision as of 09:20, 10 July 2014
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In these images, each horizontal bar represents the lifetime of a process. A processes children are below it, and parent child relationships are indicated by a dotted line from the parent going into the beginning of the child's bar. The process bars are in order of launch time (earliest first). Blue segments of the bar represent CPU activity while pink segments indicate IO. | In these images, each horizontal bar represents the lifetime of a process. A processes children are below it, and parent child relationships are indicated by a dotted line from the parent going into the beginning of the child's bar. The process bars are in order of launch time (earliest first). Blue segments of the bar represent CPU activity while pink segments indicate IO. | ||
Based on the current code, the earliest it is conceivably possible to run B2G would be in the early-init stage of init.rc. This stage was observed to be executing at around 4.8s of uptime. Realistically a lot of things would need to be changed for this to work (that is to say, a lot of things break when this is attempted). A more logical stage would be early-boot (which is not used in the default init script, however is a supported stage that occurs between post-fs-data and boot). What is notable about this stage is that, A.) if done here, B2G launches at around 5.8s and B.) It successfully runs. Sometimes. There are clearly some dependencies that are not quite guaranteed to be ready if one attempts to launch B2G this early, which could be the subject of a future investigation to see if those dependencies could be moved earlier as well. However as it stands, this only launches B2G around 2 seconds earlier. and there actually was no decrease in overall boot time observed (again dependencies not being respected comes to mind as an explanation). | Based on the current code, the earliest it is conceivably possible to run B2G would be in the early-init stage of init.rc. This stage was observed to be executing at around 4.8s of uptime. Realistically a lot of things would need to be changed for this to work (that is to say, a lot of things break when this is attempted). A more logical stage would be early-boot (which is not used in the default init script, however is a supported stage that occurs between post-fs-data and boot). What is notable about this stage is that, A.) if done here, B2G launches at around 5.8s and B.) It successfully runs. Sometimes. There are clearly some dependencies that are not quite guaranteed to be ready if one attempts to launch B2G this early, which could be the subject of a future investigation to see if those dependencies could be moved earlier as well. However as it stands, this only launches B2G around 2 seconds earlier. and there actually was no decrease in overall boot time observed (again dependencies not being respected comes to mind as an explanation, or gaia/gecko depending on some other service being initialized). | ||
[http://people.mozilla.org/~jbailey/v121-2-lesswreckless/ Related Data]. Fewer trials were done because these were just cursory feasibility tests. | [http://people.mozilla.org/~jbailey/v121-2-lesswreckless/ Related Data]. Fewer trials were done because these were just cursory feasibility tests. | ||