I've been thinking about a tool that might be useful to track kernel size changes. I'm posting this Request For Comments to get feedback, and determine if this is something that would be worthwhile to pursue. What I envision is some new kernel build targets, specifically related to gathering size information and generating a size comparison report. Some small helper scripts would be written to gather the necessary information, and generate the report. A kernel developer would type: 1) make size-baseline And kernel size information would be recorded for the current kernel (after a build, if needed). I envision this saving off the .config and System.map, the result of 'size vmlinux' and several of the 'size */builtin.o' results. Additionally (and optionally), a program could be run to acquire some size information from a running system (e.g. a newly booted system, or a system under a particular load), to include in the baseline report. All of the gathered information would be stored as the "size baseline". ------- After making some modifications, either to the source or the configuration, the developer could type: 2) make size-report The kernel size information would be recorded again, and compared with the size-baseline results. A report of differences (e.g. from bloat-o-meter and other comparison tools) would be produced. Any differences exceeding some threshhold (specified in a size-watch config file?) could be highlighted. The git commit IDs would be recorded, as well as differences between the configs used (e.g. diffconfig output). If some designated size difference exceeds a threshold (specified in the size-watch configuration) then the make could return an error, while still producing the report. This would mean that this could be used for git bisection to find a size regression. Another way to look at this, would be that a developer could pick a specific size value to monitor (for example, the static size of the network sub-system, or the size of a particular slab in the dynamic memory of a newly booted kernel). They would specify that in the size-watch config, and could monitor that size over time and under various configurations. I envision a couple of usages: 1) A developer could use this to be able to see a report about the total size increases caused by a patch they are about to submit 2) A developer could compare kernel versions for overall size changes 3) A maintainer could examine the affect of a patch on the size of their subsystem. 4) A developer could compare different kernel configs to see the impact of configuration option choices. 5) An automated tool could generate size values to associate with different config option choices (at least, starting from a consistent config set). 6) An automated tool could generate size values for each kernel version (this is what Bloatwatch does now). Bloatwatch generates information on the static size information for various kernel versions. This would have a similar purpose, but the intent would be to integrate it into the kernel build system, to allow any developer to measure the size information, and highlight and track the information of their choice. Any comments? -- Tim ============================= Tim Bird Architecture Group Chair, CE Linux Forum Senior Staff Engineer, Sony Corporation of America ============================= -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
