ImrovingAndroidBootutime提高启动时间.pptVIP

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Bootchart closeup Regions of interest Area 1 = kernel init Approx. 8 seconds in this chart Area 2 = zygote class preloading From approx. 8 to 29 seconds into boot 21 seconds Area 3 = PackageManager package scanning From approx 29 to 50 seconds into boot 21 seconds Area 4 = System Services starting From approx. 50 to 59 seconds into boot 9 seconds Logcat results (main) ADP1: preloaded 1514 classes in 11530ms Time to scan packages: 10.064 seconds N1: preloaded 1942 classes in 5360ms Time to scan packages: 8.975 seconds EVM: preloaded 1942 classes in 13619ms Time to scan packages: 19.731 seconds Logcat results (events) I/boot_progress_start( 754): 12559 I/boot_progress_preload_start( 754): 17879 I/boot_progress_preload_end( 754): 28546 I/boot_progress_system_run( 768): 29230 I/boot_progress_pms_start( 768): 29697 I/boot_progress_pms_system_scan_start( 768): 30117 I/boot_progress_pms_data_scan_start( 768): 44171 I/boot_progress_pms_scan_end( 768): 50006 I/boot_progress_pms_ready( 768): 50505 I/boot_progress_ams_ready( 768): 53166 I/boot_progress_enable_screen( 768): 56793 Problem Areas Bootloader init Kernel init Zygote class preloading Package scanning Service initialization Bootloader init Outside scope of this talk Didnt measure commercial bootloader, only development one (U-boot) Is contained within first 4 seconds on phones (I think) Kernel Init Is mostly the usual suspects ip_auto_config USB (ehci, ohci) init OMAP flash and driver initialization See initcall_debug results Just follow standard instructions for optimizing initcalls in the kernel See /Boot_Time Some of this is board-specific Depends on your flash controller Is outside scope of this talk Zygote class preloading Zygote pre-loads just under 2000 classes, and instantiates them in its heap Controlled by resource: preloaded-classes Which comes from source: frameworks/base/preloaded-classes Google developers say you can adjust this