On 06/24/2010 06:59 PM, David Turner wrote: > The problem is that you didn't count the time to do the "cat" in your > overall benchmark. > Hence, the savings you present are purely hyptohetical, even if you > implement prefetching. > > On Sun, Jun 20, 2010 at 4:31 PM, Tomei <tomei.ninge...@gmail.com > <mailto:tomei.ninge...@gmail.com>> wrote: > > Hello, > > It seems package scanning speed is greatly influenced by IO buffering: > > I did some simple experiment. I am testing with a fresh build so there > are NO apps under /data/app. > > First boot up the phone. Then do either (A) or (B): > > (A): > > # stop > # sync; echo 3 > /proc/sys/vm/drop_caches > # start > > (B): > > # stop > # sync; echo 3 > /proc/sys/vm/drop_caches > # cat /system/app/*.apk > /dev/null > # start > > case (A): � � I/PackageManager( 3114): Time to scan packages: 12.668 > seconds > case (B): � � I/PackageManager( 3189): Time to scan packages: 7.032 > seconds > > Can PackageManagerService be easily reworked so that it pre-fetches > the buffers for the "next app to scan" in a separate thread?
This sounds interesting. So based on David's response, what is 'time cat /system/app/*.apk >/dev/null' ?? > I can't just blindly run a "cat /system/app/*.apk > /dev/null" before > package scanning happens, because doing so would cost more time than > the saving indicated from above .... I'm currently looking at the package scan time as well. I instrumented PackageManagerService to log each package (so I could get the delta per package) A list of the top durations, sorted by duration, is shown below: delta log time ... 0.609 [ 29.573 ] I/PackageManager( 769): Parsing package in file: /system/framework/framework-res.apk 0.954 [ 34.127 ] I/PackageManager( 769): Parsing package in file: /system/app/Camera.apk 1.117 [ 42.870 ] I/PackageManager( 769): Parsing package in file: /data/app/ApiDemos.apk 1.148 [ 30.370 ] I/PackageManager( 769): Parsing package in file: /system/app/Music.apk 1.227 [ 37.971 ] I/PackageManager( 769): Parsing package in file: /system/app/Launcher.apk 1.453 [ 32.229 ] I/PackageManager( 769): Parsing package in file: /system/app/Gallery.apk 1.742 [ 36.104 ] I/PackageManager( 769): Parsing package in file: /system/app/Settings.apk 2.297 [ 39.370 ] I/PackageManager( 769): Parsing package in file: /system/app/Contacts.apk I noticed that the delta time, or elapsed time to load the package, is strongly related to the package size. I've been trying to read through the code to find out where the time is being spent. I've only seen parsing of AndroidManifest.xml so far, but since these always occur at the front of .apks, I wouldn't think this would account for a scan duration relating to the whole package size. Are there other resources being loaded during the package scan? Is the whole file read and processed - not just the manifest? From strace, it's clear that the accesses are via an mmapped file (there are no read syscalls in the strace), so I haven't gotten a clear picture of the read pattern of the files. There are a lot of layers of code here, (and the method tracer is broken on my platform) so it's taking me a bit of time (ha, ha) to figure out where the time is actually being spent. Any pointers or additional information would be appreciated. Thanks, -- Tim ============================= Tim Bird Architecture Group Chair, CE Linux Forum Senior Staff Engineer, Sony Network Entertainment ============================= -- unsubscribe: android-porting+unsubscr...@googlegroups.com website: http://groups.google.com/group/android-porting
