adb shell cat /proc/meminfo
MemTotal
tells you how much device memory is available outside of drivers/kernel.MemFree
tells you how much memory is currently available, checking this after booting should give you a rough guesstimate of what our max is.
To simulate what would happen in a low-memory situation you can adb shell kill <pid>
each b2g process but b2g, (Nuwa), Homescreen (use b2g-ps
to get a b2g process listing). Unfortunately Homescreen just comes back (it can be LMK'd though, so add it's USS to the MemFree total to get a better idea of an ideal MemFree value).
Get an overview of b2g application memory usage