On Aug 7, 2012, at 4:13 PM, HSSoftware <[email protected]> wrote:
> Our app, Art Authority, was just re-built with MfA 4.0.6, Android 2.3 API,
> and deployed onto both a Samsung Galaxy S 3 (Android 4.0.x) and a Google
> Nexus 7 (Android 4.1.1). On both devices the app seems to run slower than on
> the lowly original Kindle Fire (Android 2.3).
How much slower?
Android changed how grefs are handled in Android v4.0. Prior to 4.0, a gref is
a direct pointer to the Java object. Managed wrapper instance lookup is thus
equivalent to:
IJavaObject wrapper = instances [gref];
With 4.0, they're not. In order to make this work, when running on Android
v4.0+ there are extra calls to java.lang.System.identityHashCode():
IJavaObject wrapper = instances [java.lang.System.identityHashCode
(gref))];
There is thus an extra JNI call when looking up every wrapper instance.
Depending on how many object lookups are occurring, this could plausibly be
noticeable.
> Could this be something to do with building with Android 2.3 API specified,
> or the fact that SQLite moved from native to Java with Ice Cream Sandwich?
SQLite didn't move from native to Java in Ice Cream Sandwich; Android still has
libsqlite.so, and thus still has the native library.
> We are using Android.Database.Sqlite to access SQLite. Could this pose a
> performance problem?
It could, if you call into it a lot. (Anything could be a performance problem
if you cross the Mono/Dalvik border a lot; see also [0].)
- Jon
[0] http://lists.ximian.com/pipermail/monodroid/2012-July/011358.html
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