OProfile: OProfile is in mainline Linux and shipped in most distributions. OProfile can profile both user space and kernel space, and works on x86-32, x86-64, IA64, PPC, ARM, MIPS, Sparc and more (although OProfileUI has only been tested against x86-32 and ARM so far).

Client/Server: with a client/server design you can run the lightweight oprofile-server on the target device (this only links to GLib) and run the interface on your desktop machine, moving the intensive work of analysing the profile data from the target to the more powerful desktop. This also lets you profile one machine doing tasks where it is normally tricky to run a profiler, such as logging in to GNOME from GDM, by moving the control interface to another machine.

I've been fanboying Rob over this for some time now, I'm really pleased that it has finally been released. Let's go profile!