Trying to Improve Android Boot Time With Readahead改善Android启动时间和预读高速.ppt

Treadahead usage Usage: treadahead [options] [file1 [file2 ...]] -f Read list of files from /readahead_list.txt -ffile Read list of files from file -h Show this usage help -v Show verbose messages -w Re-write blocks to be preloaded, in the filesystem This may optimize the blocks for preloading -i Reduce IO scheduler priority for treadahead to idle (ionice -c 3) -j Reduce IO scheduler priority for treadahead to best effort- low -n Set noop scheduler for sda, prior to doing readahead -p Reduce scheduler priority for treadahead (nice 19) -l Output log message on start and end -e Do early exit after forking, so calling program can continue. This will redirect stdout to /dev/null, so with -v most messages are lost. -V Show version message -s Save /proc/diskstats at start and end of operation. Files are saved to /cache/debug/d1.txt and /cache/debug/d2.txt. System description Sony Internet TV Actually, the Blu-Ray player Intel Atom core (uniprocessor) Kernel version: 2.6.23 8 Gig Sony SSD System partition fileystem type: ext3 Default I/O scheduler: CFQ What I wanted to see Readahead runs in background, not affecting or delaying other processes and their I/O Reduction in time to perform class pre-loading and application package scanning Ultimately, have system boot quicker With NO software changes on device Things I tested Affect of backgrounding the readahead task Affect of process scheduler priority Affect of I/O scheduler choice Affect of setting I/O scheduling priority Affect of re-writing the data in load order Process backgrounding Init can launch things with ‘exec’ or ‘service’ ‘exec’ blocks and waits for program to exit before continuing ‘service’ processes are launched asynchronously Not sure the order I needed treadahead to start before ‘service’ items were processed by init Treadahead can run in background, returning control to ‘init’ immediately after forking into a daemon Process schedule